Mathematics Syllabus
For Class 9
Unit I: Number Systems
1. RealNumbers (18Periods)
Review of representation of natural numbers, integers, rational numbers on the number line. Representation of terminating/nonterminating recurring decimals on the number line through successive magnification. Rational numbers as recurring/terminating decimals. Operations on real numbers.
Examples of nonrecurring/nonterminating decimals. Existence of nonrational numbers (irrational numbers) such as , 23 and their representation on the number line. Explaining that every real number is represented by a unique point on the number line and conversely, every point on the number line represents a unique real number.
Definition of nth root of a real number. Existence of x for a given positive real number x and its representation on the number line with geometric proof.
Rationalisation (with precise meaning) of real numbers of the type (and their combinations) abx 1 and , xy 1 where x and y are natural numbers, a and b are integers.
Recall of laws of exponents with integral powers. Rational exponents with positive real bases (to be done by particular cases, allowing learner to arrive at the general laws).
Unit II: Algebra
1. Polynomials (23Periods)
Definition of a polynomial in one variable, its coefficients, with examples and counter-examples, its terms, zero polynomial. Degree of a polynomial. Constant, linear, quadratic, cubic polynomials; monomials, binomials, trinomials. Factors and multiples. Zeros of a polynomial. Motivate and state the Remainder Theorem with examples. Statement and proof of the Factor Theorem. Factorisation of ,,axbxca 0 2 ! where a, b and c are real numbers, and of cubic polynomials using the Factor Theorem. (v)
Recall of algebraic expressions and identities. Further verification of identities of the type (), xyzxyzxyyzzx 222 2222
()(),()() xyxyxyxyxyxyxxyy 3 3333322 !!!!!!"
()(), xyzxyzxyzxyzxyyzzx 3 333222
and their use in factorization of polynomials.
2. LinearEquationsinTwoVariables (14Periods)
Recall of linear equations in one variable. Introduction to the equation in two variables. Focus on linear equations of the type . axbyc 0 Prove that a linear equation in two variables has infinitely many solutions, and justify their being written as ordered pairs of real numbers, plotting them and showing that they lie on a line. Graph of linear equations in two variables. Examples, problems from real life, including problems on Ratio and Proportion, and with algebraic and graphical solutions being done simultaneously.
Unit III: Coordinate Geometry
1. CoordinateGeometry (6Periods)
The Cartesian plane, coordinates of a point, names and terms associated with the coordinate plane, notations, plotting points in the plane.
Unit IV: Geometry
1. IntroductiontoEuclid’sGeometry (6Periods)
History—Geometry in India and Euclid’s geometry. Euclid’s method of formalizing observed phenomenon into rigorous mathematics with definitions, common/obvious notions, axioms/postulates, and theorems. The five postulates of Euclid. Equivalent versions of the fifth postulate. Showing the relationship between axiom and theorem, for example:
(Axiom) 1. Given two distinct points, there exists one and only one line through them.
(Theorem) 2. (Prove) Two distinct lines cannot have more than one point in common.
2. LinesandAngles (13Periods)
1. (Motivate) If a ray stands on a line, then the sum of the two adjacent angles so formed is and the converse.
2. (Prove) If two lines intersect, vertically opposite angles are equal. (vi)
3. (Motivate) Results on corresponding angles, alternate angles, interior angles when a transversal intersects two parallel lines.
4. (Motivate) Lines, which are parallel to a given line, are parallel.
5. (Prove) The sum of the angles of a triangle is 180 .
6. (Motivate) If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the two interior opposite angles.
3. Triangles (20Periods)
1. (Motivate) Two triangles are congruent if any two sides and the included angle of one triangle are equal to any two sides and the included angle of the other triangle (SAS congruence).
2. (Prove) Two triangles are congruent if any two angles and the included side of one triangle are equal to any two angles and the included side of the other triangle (ASA congruence).
3. (Motivate) Two triangles are congruent if the three sides of one triangle are equal to three sides of the other triangle (SSS congruence).
4. (Motivate) Two right triangles are congruent if the hypotenuse and a side of one triangle are equal (respectively) to the hypotenuse and a side of the other triangle.
5. (Prove) The angles opposite to equal sides of a triangle are equal.
6. (Motivate) The sides opposite to equal angles of a triangle are equal.
7. (Motivate) Triangle inequalities and relation between ‘angle and facing side’ inequalities in triangles.
4. Quadrilaterals (10Periods)
1. (Prove) The diagonal divides a parallelogram into two congruent triangles.
2. (Motivate) In a parallelogram opposite sides are equal, and conversely.
3. (Motivate) In a parallelogram opposite angles are equal, and conversely.
4. (Motivate) A quadrilateral is a parallelogram if a pair of its opposite sides are parallel and equal.
5. (Motivate) In a parallelogram, the diagonals bisect each other, and conversely.
6. (Motivate) In a triangle, the line segment joining the midpoints of any two sides is parallel to the third side and is half of it, and (motivate) its converse.
(vii)
5. Area (7Periods)
Review concept of area, recall area of a rectangle.
1. (Prove) Parallelograms on the same base and between the same parallels have the same area.
2. (Motivate) Triangles on the same (or equal base) base and between the same parallels are equal in area.
6. Circles (15Periods)
Through examples, arrive at definitions of circle and related concepts— radius, circumference, diameter, chord, arc, secant, sector segment, subtended angle.
1. (Prove) Equal chords of a circle subtend equal angles at the centre, and (motivate) its converse.
2. (Motivate) The perpendicular from the centre of a circle to a chord bisects the chord and conversely, the line drawn through the centre of a circle to bisect a chord is perpendicular to the chord.
3. (Motivate) There is one and only one circle passing through three given noncollinear points.
4. (Motivate) Equal chords of a circle (or of congruent circles) are equidistant from the centre (or their respective centres), and conversely.
5. (Prove) The angle subtended by an arc at the centre is double the angle subtended by it at any point on the remaining part of the circle.
6. (Motivate) Angles in the same segment of a circle are equal.
7. (Motivate) If a line segment joining two points subtends equal angles at two other points lying on the same side of the line containing the segment, the four points lie on a circle.
8. (Motivate) The sum of either of the pair of the opposite angles of a cyclic quadrilateral is 180, and its converse.
7. Constructions (10Periods)
1. Construction of bisectors of line segments and angles of measure 60, 90, 45, etc., equilateral triangles.
2. Construction of a triangle given its base, sum/difference of the other two sides and one base angle.
3. Construction of a triangle of given perimeter, and base angles.
(viii)
Unit V: Mensuration
1. Areas (4Periods)
Area of a triangle using Heron’s formula (without proof) and its application in finding the area of a quadrilateral.
2. SurfaceAreasandVolumes (12Periods)
Surface areas and volumes of cubes, cuboids, spheres (including hemispheres) and right circular cylinders/cones.
Unit VI: Statistics and Probability
1. Statistics (13Periods)
Introduction to Statistics: Collection of data, presentation of data— tabular form, ungrouped/grouped, bar graphs, histograms (with varying base lengths), frequency polygons. Mean, median and mode of ungrouped data.
2. Probability (9Periods)
History, repeated experiments and observed frequency approach to probability. Focus is on empirical probability. (A large amount of time to be devoted to group and to individual activities to motivate the concept; the experiments to be drawn from real-life situations, and from examples used in the chapter on statistics.)
Time:3Hours
CLASS 9
Max.Marks:80
The weightage or the distribution of marks over different dimensions of the question paper shall be as follows:
Weightage to Content/Subject Units
S. No.UnitMarks
1.Number Systems
Real Numbers
2.Algebra Polynomials
Linear Equations in Two Variables
3.Coordinate Geometry
Coordinate Geometry
4.Geometry
Introduction to Euclid’s Geometry
Lines and Angles
Triangles
Quadrilaterals
Area
Circles
Constructions
5.Mensuration
Area of a Triangle using Heron’s Formula Surface Areas and Volumes
6.Statistics and Probability Statistics
Probability
INTRODUCTION
We have learnt about various types of numbers in our earlier classes. Let us review them and learn more about numbers.
NATURAL NUMBERS Counting numbers are called natural numbers. The collection of natural numbers is denoted by N and is written as {,,,,,,…}. N 123456
REMARKS (i) The least natural number is 1.
(ii) There are infinitely many natural numbers.
WHOLE NUMBERS All natural numbers together with 0 form the collection W of all whole numbers, written as {,,,,,,…}. W 012345
REMARKS (i) The least whole number is 0.
(ii) There are infinitely many whole numbers.
(iii) Every natural number is a whole number.
(iv) All whole numbers are not natural numbers, as 0 is a whole number which is not a natural number.
INTEGERS All natural numbers, 0 and negatives of natural numbers form the collection of all integers. It is represented by Z after the German word ‘zahlen’ meaning ‘to count’. Thus, we write {…,,,,,,,,,,,,…}. Z 54321012345
REMARKS (i) 0 is neither negative nor positive.
(ii) There are infinitely many integers.
(iii) Every natural number is an integer.
(iv) Every whole number is an integer.
REPRESENTATION OF INTEGERS ON NUMBER LINE
A number line is a visual representation of numbers on a graduated straight line. To represent integers on the number line, draw a line XY which extends endlessly in both the directions, as indicated by the arrowheads in the diagram below.
Secondary School Mathematics for Class 9
Take any point O on this line. Let this point represent the integer 0 (zero). Now, taking a fixed length, called unit length, set off equal distances to the right as well as to the left of O.
On the right-hand side of O, the points at distances of 1 unit, 2 units, 3 units, 4 units, 5 units, etc., from O denote respectively the positive integers 1, 2, 3, 4, 5, etc.
Similarly, on the left-hand side of O, the points at distances of 1 unit, 2 units, 3 units, 4 units, 5 units, etc., from O denote respectively the negative integers –1, –2, –3, –4, –5, etc.
Since the line can be extended endlessly on both sides of O, it follows that we can represent each and every integer by some point on this line.
For instance, starting from O and moving to its right, after 836 units, we get a point which represents the integer 836.
Similarly, starting from O and moving to its left, a point after 750 units, represents the integer ‘–750’.
Thus, each and every integer can be represented by some point on the number line.
RATIONAL NUMBERS The numbers of the form , q p where p and q are integers and , q 0 ! are known as rational numbers. The collection of rational numbers is denoted by Q and is written as
‘Rational’ comes from the word ‘ratio’ and Q comes from the word ‘quotient’.
Thus, ,,,, 4 1 2 3 79 11 2002 2001 etc., are all rational numbers.
REMARKS (i) There are infinitely many rational numbers.
(ii) There is no least or greatest rational number.
(iii) 0 is a rational number, since we can write, · 0 1 0
(iv) Every natural number is a rational number since we can write, ,,, 1 1 1 2 1 2 3 1 3 etc.
(v) Every integer is a rational number since an integer a can be written as , a 1 e.g., , 31 1 31 0 1 0 and · 79 1 79
Hence, rational numbers include natural numbers, whole numbers and integers.
EQUIVALENT RATIONAL NUMBERS Rational numbers do not have a unique representation in the form , q p where p and q are integers and . q 0 !
Thus, 2 1 4
These are known as equivalent rational numbers.
SIMPLEST FORM OF A RATIONAL NUMBER A rational number q p is said to be in its simplest form, if p and q are integers having no common factor other than 1 (that is, p and q are co-primes) and . q 0 !
Thus, the simplest form of each of ,,,, 4 2 6 3 8 4 10 5 etc., is · 2 1
Similarly, the simplest form of 9 6 is 3 2 and that of 133 95 is · 7 5
EXAMPLE 1 Write four rational numbers equivalent to · 7 4
SOLUTION We have
Thus, four rational numbers equivalent to 7 4 are ,, 14 8 21 12 28 16 and · 25 20
REPRESENTATION OF RATIONAL NUMBERS ON REAL LINE
Draw a line XY which extends endlessly in both the directions. Take a point O on it and let it represent 0 (zero).
Taking a fixed length, called unit length, mark off OA 1 unit.
The midpoint B of OA denotes the rational number · 2 1 Starting from O, set off equal distances each equal to OB 2 1 unit.
Secondary School Mathematics for Class 9
From the point O, on its right, the points at distances equal to OB, 2OB, 3OB, 4OB, etc., denote respectively the rational numbers ,,,, 2 1 2 2 2 3 2 4 etc.
Similarly, from the point O, on its left, the points at distances equal to OB, 2OB, 3OB, 4OB, etc., denote respectively the rational numbers ,, 2 1 2 2 ,, 2 3 2 4 etc.
Thus, each rational number with 2 as its denominator can be represented by some point on the number line.
Next, draw the line XY. Take a point O on it representing 0. Let OA 1 unit. Divide OA into three equal parts with OC as the first part. Then, C represents the rational number 3 1
From the point O, set off equal distances, each equal to OC 3 1 unit on both sides of O.
The points at distances equal to OC, 2OC, 3OC, 4OC, etc., from the point O on its right denote respectively the rational numbers ,,,, 3 1 3 2 3 3 3 4 etc.
Similarly, the points at distances equal to ,,,, OCOCOCOC 234 etc., from the point O on its left denote respectively the rational numbers , 3 1 ,,, 3 2 3 3 3 4 etc.
Thus, each rational number with 3 as its denominator can be represented by some point on the number line (or, the real line).
Proceeding in this manner, we can represent each and every rational number by some point on the line.
EXAMPLE 2 Represent (i) 2 8 3 and (ii) 1 7 5 on real line.
SOLUTION
Draw a line XY and taking a fixed length as unit length, represent integers on this line.
(i) On the right of O, take OA 1 unit. Then, OB 2 units.
Divide the 3rd unit BC into 8 equal parts.
BP represents 8 3 of a unit. Therefore, P represents · 2 8 3
(ii) On the left of O, take OD 1 unit.
Divide the 2nd unit DE into 7 equal parts.
DQ represents 7 5 of a unit. Therefore, Q represents · 1 7 5
EXAMPLE 3 Represent (i) 5 8 and (ii) 7 11 on the number line.
SOLUTION Draw a line XY and taking a fixed length as unit length, represent integers on this line.
(i) · 5 8 1 5 3
On the right of O, take OA 1 unit.
Divide the 2nd unit AB into 5 equal parts.
AP represents 5 3 of a unit. Therefore, P represents · 1 5 3
(ii) · 7 11 1 7 4
On the left of O, take OD 1 unit.
Divide the 2nd unit DE into 7 equal parts.
Then, DQ represents 7 4 of a unit. Therefore, Q represents · 7 11
FINDING RATIONAL NUMBERS BETWEEN TWO GIVEN RATIONAL NUMBERS
METHOD 1 Suppose we are required to find one rational number between two rational numbers x and y such that .xy Then, () xy 2 1 is a rational number lying between x and y
EXAMPLE 4
Find a rational number lying between (i) 3 1 and ; 2 1 (ii) 3 2 and · 4 3
SOLUTION (i) Let x 3 1 and · y 2 1
required rational number lying between x and y
() xy 2
Secondary School Mathematics for Class 9
required rational number lying between 3 2 and 4 3
EXAMPLE 5 Find three rational numbers between 2 and 3 [2014]
SOLUTION A rational number lying between 2 and 3 is [()()], 2 1 23
i.e., · 2 5
Now, a rational number lying between 2 and 2 5 is
METHOD 2 Suppose we are required to find n rational numbers between two rational numbers, x and y with like denominators.
Then, we convert the given rational numbers into equivalent rational numbers by multiplying the numerator and denominator by a suitable number, usually (). n 1
Now, the required rational numbers may be manually chosen.
EXAMPLE 6 Find five rational numbers between · and 5 3 5 4 [2015] SOLUTION Let . n 5
We convert 5 3 and 5 4 into equivalent rational numbers by multiplying the numerator and denominator by (), n 1 i.e., 6. Thus, 5 3
Hence, five rational numbers between 5 3 and 5 4 are ,, 20 19 3 2 ,, 10 7 15 11 and · 30 23
EXAMPLE 7 Find six rational numbers between 3 and 4. [2015] SOLUTION Let . n 6
We convert 3 and 4 into equivalent rational numbers using () n 17 as multiplying factor.
Hence, six rational numbers between 3 and 4 are
and 7 25 7 26 7 27 EXAMPLE 8 Insert 10 rational numbers between 13 5 and · 13 6
8
Secondary School Mathematics for Class 9
EXAMPLE 9 Insert 100 rational numbers between 11 4 and · 11 7 SOLUTION Clearly, we have
Hence, 100 rational numbers between 11 4 and 11 7 are
METHOD 3 Suppose we are required to find n rational numbers between two given rational numbers x and y (especially those with unlike denominators) such that .xy Let · () () d n yx 1
Then, n rational numbers lying between x and y are (),(),
(),,(). xdxnd 3…
2
REMARK There are infinitely many rational numbers between any two given rational numbers.
EXAMPLE 10 Insert five rational numbers between 3 2 and · 4 3
So, the five rational numbers between 3 2 and 4 3 are (),(),(),()(), and xdxdxdxdxd 2345
EXAMPLE 11 Find nine rational numbers between 0 and 0.1.
SOLUTION Here ,.. and xyn0019
Hence, the required numbers between 0 and 0.1 are (),(),(),(),(),(),(),
i.e. 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08 and 0.09, i.e. ,,,,,,,
and ,
Hence, nine rational numbers between 0 and 0.1 are
and
f EXERCISE 1A
1. Is zero a rational number? Justify.
2. Represent each of the following rational numbers on the number line:
3. Find a rational number between (i) and 8 3
and 2 1
4. Find three rational numbers lying between 5 3 and · 8 7
[2015]
How many rational numbers can be determined between these two numbers? [2011]
5. Find four rational numbers between 7 3 and 7 5 [2010]
6. Find six rational numbers between 2 and 3.
7. Find five rational numbers between 5 3 and · 3 2
8. Insert 16 rational numbers between 2.1 and 2.2.
9. State whether the following statements are true or false. Give reasons for your answer.
(i) Every natural number is a whole number.
(ii) Every whole number is a natural number.
(iii) Every integer is a whole number.
(iv) Every integer is a rational number.
(v) Every rational number is an integer.
(vi) Every rational number is a whole number.
ANSWERS (EXERCISE 1A)
1. Yes, because 0 can be written as 1 0 which is of the form , q p where p and q are integers and . q 0 !
3. (i) 80 31 (ii) 1.35 (iii) 4 1 (iv) 40 23 (v) 6 1
4. ,,
,,,,, 7
8. 2.105, 2.11, 2.115, 2.12, 2.125, 2.13, 2.135, 2.14, 2.145, 2.15, 2.155, 2.16, 2.165, 2.17, 2.175, 2.18
9. (i) True
(ii) False; 0 is a whole number which is not a natural number.
(iii) False; negative integers are not whole numbers.
(iv) True; every integer can be written in the form , q p where p and q are integers and . q 0 !
(v) False; fractional numbers are not integers.
(vi) False; fractional numbers are not whole numbers.
DECIMAL REPRESENTATION OF RATIONAL NUMBERS
Every rational number q p can be expressed as a decimal. On dividing p by q, two possibilities arise
(i) The remainder becomes zero and the division concludes after a finite number of steps. In this case, the decimal expansion obtained also terminates or ends.
(ii) The remainder never becomes zero and a repeating string of remainders is obtained. In this case, we get a digit or a block of digits repeating in the decimal expansion.
Thus, we have two types of decimal expressions:
1. TERMINATING DECIMAL A decimal that ends after a finite number of digits is called a terminating decimal.
Examples We have (i) ., 4 1 025 (ii) ., 8 5 0625 (iii) 2
41025 )(.. 850625 . )( 51326
Thus, each of the numbers , 4 1 8 5 and 2 5 3 can be expressed as a terminating decimal.
IMPORTANT RULE A rational number q p is expressible as a terminating decimal only when prime factors of q are 2 and 5 only.
Examples Each one of the numbers ,,, 2 1 4 3 20 7 25 13 is a terminating decimal since the denominator of each has no prime factors other than 2 and 5.
EXAMPLE Without actual division, find which of the following rational numbers are terminating decimals: (i) 32 5 (ii) 24 11 (iii) · 80 27
SOLUTION
(i) Denominator of 32 5 is 32.
And, . 322 5
32 has no prime factors other than 2.
So, 32 5 is a terminating decimal.
(ii) Denominator of 24 11 is 24.
And, 2423. 3 #
Thus, 24 has a prime factor 3, which is other than 2 and 5.
24 11 is not a terminating decimal.
(iii) Denominator of 80 27 is 80.
And, 8025. 4 #
Thus, 80 has no prime factors other than 2 and 5.
80 27 is a terminating decimal.
2. REPEATING (OR RECURRING) DECIMALS A decimal in which a digit or a set of digits is repeated periodically, is called a repeating, or a recurring, decimal.
In a recurring decimal, we place a bar over the first block of the repeating digits and omit the other repeating blocks.
Examples
(iii) . 7 15 2142857142857… (iv) . 6 11 18333… . 2142857 . 183 .… )( 715214285714 .… )( 6111833
You must have noticed a repeating string of remainders in each of the above cases.
In (i), it is 2, 2, …; in (ii), it is 8, 3, 8, 3, … .
In (iii), it is 1, 3, 2, 6, 4, 5, 1, …; in (iv), it is 5, 2, 2, 2, … .
Kindly note that the number of entries in the repeating string of remainders is less than the divisor.
In , 3 2 only one number 2 repeats itself and the divisor is 3.
In , 7 15 a set of 6 digits, namely 132645, repeats itself and the divisor is 7.
Thus, if the divisor is n then the maximum number of entries in the repeating block of digits in the decimal expansion of n 1 is (). n 1
LENGTH OF PERIOD Repeated number of decimal places in a rational number is called the length of its period.
Example .. 7 15 2142857
So, the length of its period is 6.
SPECIAL CHARACTERISTICS OF RATIONAL NUMBERS
(i) Every rational number is expressible either as a terminating decimal or as a nonterminating recurring decimal.
Secondary School Mathematics for Class 9
(ii) A number whose decimal expansion is terminating or nonterminating recurring is rational.
SOLVED EXAMPLES
EXAMPLE 1
Express 3 8 1 in decimal form. SOLUTION We have · 3 8 1 8 25 By actual division, we have
EXAMPLE 2
Express 11 2 in decimal form.
EXAMPLE 3 Write 13 3 in decimal form and say what kind of decimal representation it has. [2010]
SOLUTION By actual division, we have
Clearly, 13 3 has a nonterminating recurring decimal representation.
EXAMPLE 4 Find the decimal expansion of · 7 1 Can you predict what the decimal expansions of ,,,,
are, without actually doing the long division? If so, how? SOLUTION By long division, we
Secondary School Mathematics for Class 9
EXAMPLE 5 What can the maximum number of digits be in the repeating block of digits in the decimal expansion of 17 1 ? Perform the division to check your answer.
By long division, we have
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Chemical
Benzyl iodide
Benzyl chloride
Bromoacetone
Bromobenzylcyanide
Bromomethylethylketone
Benzyl bromide
Chlorine
Chlorosulfonic acid
Chloroacetone
Chlorobenzene (as solvent)
Chloropicrin
Cyanogen bromide
Dichloromethylether
Belligerent Effect
Means of Projection
French Lachrymatory Artillery shell
French Lachrymatory Artillery shell
French Lachrymatory Artillery shell
Lethal
French Lachrymatory Artillery shell
German Lachrymatory Artillery shell
Lethal Artillery shell
German Lachrymatory Artillery shell
French
German Lethal Cylinders
British (cloud gas)
French
American
German Irritant Hand grenades, light minenwerfer
French Lachrymatory Artillery shell
German Lachrymatory Artillery shell
British Lethal Artillery shell
French Lachrymatory Trench mortar bombs
German Projectors
American
Austrian Lethal Artillery shell
German Lachrymatory Artillery shell (as solvent)
Diphenylchloroarsine
Dichloroethylsulfide
Ethyldichloroarsine
Ethyliodoacetate
Hydrocyanic acid
Methylchlorosulfonate
Monochloromethylchloroformate
Phosgene
German Sternutatory Artillery shell
Lethal
German Vesicant Artillery shell
French Lethal
British Irritant
American
German Lethal Artillery shell
British Lachrymatory Artillery shell, 4-in. Stokes’ mortars, hand grenades
French (In mixtures. See below) Lachrymatory
German Irritant Minenwerfer
French Lachrymatory Lachrymatory
British Lethal Projectors, French trench mortars, German artillery shell, American cylinders
Chemical
Belligerent Effect
Means of Projection
Phenylcarbylaminechloride German Lachrymatory Artillery shell Irritant
Trichlormethylchloroformate German Lethal Artillery shell
Stannic chloride British Irritant Hand grenades
French Cloud forming Artillery American Projectors 4-in Stokes’ mortar bombs
Sulfuric anhydride German Irritant Hand grenades, minenwerfer, artillery shell
Xylyl bromide German Lachrymatory Artillery shell
TABLE I—Continued
Chemical Belligerent Effect
M [4]
Means of Projection
Bromoacetone (80%) and French Lachrymatory Artillery shell
Chloroacetone (20%) Lethal
Chlorine (50%) and British Lethal Cylinders
Phosgene (50%) German
Chlorine (70%) and British Lethal Cylinders
Chloropicrin (30%) Lachrymatory
Chloropicrin (65%) and British Lethal Cylinders
Hydrogen sulfide (35%) Lachrymatory
Chloropicrin (80%) and British Lethal Artillery shell
Stannic chloride (20%) French Lachrymatory Trench mortar bombs American Irritant Projectors
Chloropicrin (75%) and Lethal Artillery shell
Phosgene (25%) British Lachrymatory Trench mortar bombs, projectors
Dichloroethyl sulfide (80%) German Vesicant and Chlorobenzene (20%) French Lethal Artillery shell
British American
Ethyl carbazol (50%) and German Sternutatory Artillery shell
Diphenylcyanoarsine (50%) Lethal
Ethyldichloroarsine (80%) and German Lethal Artillery shell
Dichloromethylether (20%) Lachrymatory
Ethyliodoacetate (75%) and Artillery shell, Alcohol (25%) British Lachrymatory 4-in Stokes’ mortars,
Chemical
Hydrocyanic acid (55%)
Chloroform (25%) and Arsenious chloride (20%)
Hydrocyanic acid (50%),
Belligerent Effect
Means of Projection hand grenades
British Lethal Artillery shell
Arsenious chloride (30%), French Lethal Artillery shell
Stannic chloride (15%) and Chloroform (5%)
Phosgene (50%) and British Lethal Artillery shell
Arsenious chloride (50%)
Dichloroethyl sulfide (80%) German Vesicant and Carbon tetrachloride (20%) French Lethal Artillery shell British American
Phosgene (60%) and British Lethal Artillery shell
Stannic chloride (40%) French Irritant
Methyl sulfate (75%) and French Lachrymatory Artillery shell
Chloromethyl sulfate (25%) Irritant
(2) To simulate the presence of a toxic gas. This may be done either by using a substance whose odor in the field strongly suggests that of the gas in question, or by so thoroughly associating a totally different odor with a particular “gas” in normal use that, when used alone, it still seems to imply the presence of that gas. This use of imitation gas would thus be of service in economizing the use of actual “gas” or in the preparation of surprise attacks.
While there was some success with this kind of “gas,” very few such attacks were really carried out, and these were in connection with projector attacks.
G U
Table I gives a list of all the gases used by the various armies, the nation which used them, the effect produced and the means of projection used.
Table II gives the properties of the more important war cases (compiled by Major R. E. Wilson, C. W. S.).
The gases used by the Germans may also be classified by the names of the shell in which they were used. Table III gives such a classification.
M A S
In selecting markings for American chemical shell, red bands were used to denote persistency, white bands to denote non-persistency and lethal properties, yellow bands to denote smoke, and purple bands to denote incendiary action. The number of bands indicates the relative strength of the property indicated; thus, three red bands denote a gas more persistent than one red band.
The following shell markings were actually used:
1 White Diphenylchloroarsine
2 White Phosgene
1 White, 1 red Chloropicrin
1 White, 1 red, 1 white 75% Chloropicrin, 25% Phosgene 1 White, 1 red, 1 yellow 80% Chloropicrin, 20% Stannic Chloride 1 Red Bromoacetone
TABLE III
G S
Name of Shell Shell Filling
Nature of Effect
B-shell [K₁ shell (White B or BM)] Bromoketone Lachrymator
Blue Cross
(Bromomethylethyl ketone)
(a) Diphenylchloroarsine Sternutator
(b) Diphenylcyanoarsine Sternutator
(c) Diphenylchloroarsine, Ethyl carbazol
C-shell (Green Cross) (White C) Superpalite Asphyxiant
D-shell (White D) Phosgene Lethal
Green Cross
Green Cross 1
(a) Superpalite Asphyxiant
(b) Phenylcarbylaminechloride
Superpalite 65%, Asphyxiant
Chloropicrin 35%
Name of Shell Shell Filling
Superpalite,
Green Cross 2
Green Cross 3
Nature of Effect
Phosgene, Asphyxiant
Diphenylchloroarsine
Ethyldichloroarsine, (Yellow Cross 1)
K-shell (Yellow)
T-shell (Black or green T)
Yellow Cross
Yellow Cross 1
Methyldibromoarsine, Asphyxiant
Dichloromethyl ether
Chloromethylchloroformate Asphyxiant (Palite)
Xylyl bromide, Lachrymator Bromo ketone
Mustard gas, Vesicant
Diluent (CCl₄, C₆H₅Cl, C₆H₅NO₂)
See Green Cross 3
CHAPTER III
DEVELOPMENT OF THE CHEMICAL WARFARE SERVICE
Modern chemical warfare dates from April 22, 1915. Really, however, it may be said to have started somewhat earlier, for Germany undoubtedly had spent several months in perfecting a successful gas cylinder and a method of attack. The Allies, surprised by such a method of warfare, were forced to develop, under pressure, a method of defense, and then, when it was finally decided to retaliate, a method of gas warfare. “Offensive organizations were enrolled in the Engineer Corps of the two armies and trained for the purpose of using poisonous gases; the first operation of this kind was carried out by the British at the battle of Loos in September, 1915.
“Shortly after this the British Army in the field amalgamated all the offensive, defensive, advisory and supply activities connected with gas warfare and formed a ‘Gas Service’ with a Brigadier General as Director. This step was taken almost as a matter of necessity, and because of the continually increasing importance of the use of gas in the war (Auld).”
At once the accumulation of valuable information and experience was started. Later this was very willingly and freely placed at the disposal of American workers. Too much cannot be said about the hearty co-operation of England and France. Without it and the later exchange of information on all matters regarding gas warfare, the progress of gas research in all the allied countries would have been very much retarded.
While many branches of the American Army were engaged in following the progress of the war during 1915-1916, the growing importance of gas warfare was far from being appreciated. When the
United States declared war on Germany April 6, 1917, there were a few scattered observations on gas warfare in various offices of the different branches, but there was no attempt at an organized survey of the field, while absolutely no effort had been made by the War Department to inaugurate research in a field that later had 2,000 men alone in pure research work. Equally important was the fact that no branch of the Service had any idea of the practical methods of gas warfare.
The only man who seemed to have the vision and the courage of his convictions was Van H. Manning, Director of the Bureau of Mines. Since the establishment of the Bureau in 1908 it had maintained a staff of investigators studying poisonous and explosive gases in mines, the use of self-contained breathing apparatus for exploring mines filled with noxious gases, the treatment of men overcome by gas, and similar problems. At a conference of the Director of the Bureau with his Division Chiefs, on February 7, 1917, the matter of national preparedness was discussed, and especially the manner in which the Bureau could be of most immediate assistance with its personnel and equipment. On February 8, the Director wrote C. D. Walcott, Chairman of the Military Committee of the National Research Council, pointing out that the Bureau of Mines could immediately assist the Navy and the Army in developing, for naval or military use, special oxygen breathing apparatus similar to that used in mining. He also stated that the Bureau could be of aid in testing types of gas masks used on the fighting lines, and had available testing galleries at the Pittsburgh experiment station and an experienced staff. Dr. Walcott replied on February 12 that he was bringing the matter to the attention of the Military Committee.
A meeting was arranged between the Bureau and the War College, the latter organization being represented by Brigadier General Kuhn and Major L. P. Williamson. At this conference the War Department enthusiastically accepted the offer of the Bureau of Mines and agreed to support the work in every way possible.
The supervision of the research on gases was offered to Dr. G. A. Burrell, for a number of years in charge of the chemical work done by the Bureau in connection with the investigation of mine gases and
natural gas. He accepted the offer on April 7, 1917. The smoothness with which the work progressed under his direction and the importance of the results obtained were the result of Colonel Burrell’s great tact, his knowledge of every branch of research under investigation and his imagination and general broad-mindedness.
Once, however, that the importance of gas warfare had been brought to the attention of the chemists of the country, the response was very eager and soon many of the best men of the university and industrial plants were associated with Burrell in all the phases of gas research. The staff grew very rapidly and laboratories were started at various points in the East and Middle West.
It was immediately evident that there should be a central laboratory in Washington to co-ordinate the various activities and also to considerably enlarge those activities under the joint direction of the Army, the Navy and the Bureau of Mines. Fortunately a site was available for such a laboratory at the American University, the use of the buildings and grounds having been tendered President Wilson on April 30, 1917. Thus originated the American University Experiment Station, later to become the Research Division of the Chemical Warfare Service.
Meanwhile other organizations were getting under way The procurement of toxic gases and the filling of shell was assigned to the Trench Warfare Section of the Ordnance Department. In June, 1917, General Crozier, then Chief of the Ordnance Department, approved the general proposition of building a suitable plant for filling shell with toxic gas. In November, 1917, it was decided to establish such a plant at Gunpowder Neck, Maryland. Owing to the inability of the chemical manufacturers to supply the necessary toxic gases, it was further decided, in December, 1917, to erect at the same place such chemical plants as would be necessary to supply these gases. In January, 1918, the name was changed to Edgewood Arsenal, and the project was made a separate Bureau of the Ordnance Department, Col. William H. Walker, of the Massachusetts Institute of Technology, being soon afterwards put in command.
While, during the latter part of the War, gas shell were handled by the regular artillery, special troops were needed for cylinder attacks, Stokes’ mortars, Livens’ projectors and for other forms of gas warfare. General Pershing early cabled, asking for the organization and training of such troops, and recommended that they be placed, as in the English Army, under the jurisdiction of the Engineer Corps. On August 15, 1917, the General Staff authorized one regiment of Gas and Flame troops, which was designated the “30th Engineers,” and was commanded by Major (later Colonel) E. J. Atkisson. This later became the First Gas Regiment, of the Chemical Warfare Service.
About this time (September, 1917) the need of gas training was recognized by the organization of a Field Training Section, under the direction of the Sanitary Corps, Medical Department. Later it was recognized that neither the Training Section nor the Divisional Gas Officers should be under the Medical Department, and, in January, 1918, the organization was transferred to the Engineer Corps.
All of these, with the exception of the Gas and Flame regiment, were for service on this side The need for an Overseas force was recognized and definitely stated in a letter, dated August 4, 1917. On September 3, 1917, an order was issued establishing the Gas Service, under the command of Lt. Col. (later Brigadier General) A. A. Fries, as a separate Department of the A. E. F. in France. In spite of a cable on September 26th, in which General Pershing had said
“Send at once chemical laboratory, complete equipment and personnel, including physiological and pathological sections, for extensive investigation of gases and powders....”
it was not until the first of January, 1918, that Colonel R. F. Bacon of the Mellon Institute sailed for France with about fifty men and a complete laboratory equipment.
Meantime a Chemical Service Section had been organized in the United States. This holds the distinction of being the first recognition of chemistry as a separate branch of the military service in any country or any war. This was authorized October 16, 1917, and was
to consist of an officer of the Engineers, not above the rank of colonel, who was to be Director of Gas Service, with assistants, not above the rank of lieutenant colonel from the Ordnance Department, Medical Department and Chemical Service Section. The Section itself was to consist of 47 commissioned and 95 non-commissioned officers and privates. Colonel C. L. Potter, Corps of Engineers, was appointed Director and Professor W. H. Walker was commissioned Lieutenant Colonel and made Assistant Director of the Gas Service and Chief of the Chemical Service Section. This was increased on Feb. 15, 1918 to 227 commissioned and 625 enlisted men, and on May 6, 1918 to 393 commissioned and 920 enlisted men. Meanwhile Lt. Col. Walker had been transferred to the Ordnance and Lt. Col. Bogert had been appointed in his place.
At this time practically every branch of the Army had some connection with Gas Warfare. The Medical Corps directed the Gas Defense production. Offense production was in the hands of the Ordnance Department. Alarm devices, etc., were made by the Signal Corps. The Engineers contributed their 30th Regiment (Gas and Flame) and the Field Training Section. The Research Section was still in charge of the Bureau of Mines, in spite of repeated attempts to militarize it. And in addition, the Chemical Service Section had been formed primarily to deal with overseas work. While the Director of the Gas Service was expected to co-ordinate all these activities, he was given no authority to control policy, research or production.
In order to improve these conditions Major General Wm. L. Sibert, a distinguished Engineer Officer who built the Gatun Locks and Dam of the Panama Canal and who had commanded the First Division in France, was appointed Director of the Chemical Warfare Service on May 11, 1918. Under his direction the Chemical Warfare Service was organized with the following Divisions:
Overseas
Research
Development
Brigadier General Amos A. Fries
Colonel G. A. Burrell
Colonel F. M. Dorsey
Gas Defense Production
Gas Offense Production
Medical
Proving
Administration
Gas and Flame
Colonel Bradley Dewey
Colonel Wm. H. Walker
Colonel W. J. Lyster
Lt. Col. W. S. Bacon
Brigadier General H. C.
Newcomer
Colonel E. J. Atkisson
The final personnel authorized, though never reached owing to the signing of the Armistice, was 4,066 commissioned officers and 44,615 enlisted men; this was including three gas regiments of eighteen companies each.
General Sibert brought with him not only an extended experience in organizing and conducting big business, but a strong sympathy for the work and an appreciation of the problem that the American Army was facing in France. He very quickly welded the great organization of the Chemical Warfare Service into a whole, and saw to it that each department not only carried on its own duties but co-operated with the others in carrying out the larger program, which, had the war continued, would have beaten the German at his own game.
More detailed accounts will now be given of the various Divisions of the Chemical Warfare Service.
A D
The Administration Division was the result of the development which has been sketched in the preceding pages. It is not necessary to review that, but the organization as of October 19, 1918 will be given:
Director Major General Wm.
Staff:
Medical Officer
Ordnance Officer
British Military Mission
Assistant Director
Office Administration
Relations Section
Personnel Section
Contracts and Patents
Section
Finance Section
Requirements and Progress
Section
Confidential Information
Section
Transportation Section
Training Section
Procurement Section
L. Sibert
Colonel W. J. Lyster
Lt. Col. C. B. Thummel
Major J. H. Brightman
Colonel H. C. Newcomer
Major W. W. Parker
Colonel M. T. Bogert
Major F. E. Breithut
Captain W. K. Jackson
Major C. C. Coombs
Capt. S. M. Cadwell
Major S. P. Mullikin
Captain H. B. Sharkey
Lt. Col. G. N. Lewis
Lt. Col. W. J. Noonan
The administrative offices were located in the Medical Department Building. The function of most of the sections is indicated by their names.
The Industrial Relations Section was created to care for the interests of the industrial plants which were considered as essential war industries. Through its activity many vitally important industries were enabled to retain, on deferred classification or on indefinite
furlough, those skilled chemists without which they could not have maintained a maximum output of war munitions.
In the same way the University Relations Section cared for the educational and research institutions. In this way our recruiting stations for chemists were kept in as active operation as war conditions permitted.
Another important achievement of the Administration Section was to secure the order from The Adjutant General, dated May 28, 1918, that read:
“Owing to the needs of the military service for a great many men trained in chemistry, it is considered most important that all enlisted men who are graduate chemists should be assigned to duty where their special knowledge and training can be fully utilized.
“Enlisted men who are graduate chemists will not be sent overseas unless they are to be employed on chemical duties....”
While this undoubtedly created a great deal of feeling among the men who naturally were anxious to see actual fighting in France, it was very important that this order be carried out in order to conserve our chemical strength. The following clipping from the September, 1918, issue of The Journal of Industrial and Engineering Chemistry shows the result of this order.
“C C
“As the result of the letter from The Adjutant General of the Army, dated May 28, 1918, 1,749 chemists have been reported on. Of these the report of action to August 1, 1918, shows that 281 were
ordered to remain with their military organization because they were already performing chemical duties, 34 were requested to remain with their military organization because they were more useful in the military work which they were doing, 12 were furloughed back to industry, 165 were not chemists in the true sense of the word and were, therefore, ordered back to the line, and 1,294 now placed in actual chemical work. There were being held for further investigation of their qualifications on August 1, 1918, 432 men. The remaining 23 men were unavailable for transfer, because they had already received their overseas orders.
“The 1,294 men, who would otherwise be serving in a purely military capacity and whose chemical training is now being utilized in chemical work, have, therefore, been saved from waste.
“Each case has been considered individually, the man’s qualifications and experience have been studied with care, the needs of the Government plants and bureaus have been considered with equal care, and each man has been assigned to the position for which his training and qualifications seem to fit him best.
“Undoubtedly, there have been some cases in which square pegs have been fitted into round holes, but, on the whole, it is felt that the adjustments have been as well as could be expected under the circumstances.”
R D
The American University Experiment Station, established by the Bureau of Mines in April, 1917, became July 1, 1918 the Research Division of the Chemical Warfare Service. For the first five months
work was carried out in various laboratories, scattered over the country. In September, 1917, the buildings of the American University became available; a little later portions of the new chemical laboratory of the Catholic University, Washington, were taken over. Branch laboratories were established in many of the laboratories of the Universities and industrial plants, of which Johns Hopkins, Princeton, Yale, Ohio State, Massachusetts Institute of Technology, Harvard, Michigan, Columbia, Cornell, Wisconsin, Clark, Bryn Mawr, Nela Park and the National Carbon Company were active all through the war
At the time of the signing of the armistice the organization of the Research Division was as follows:
Col. G. A. Burrell Chief of Research Division
Dr. W. K. Lewis In Charge of Defense Problems
Dr. E. P. Kohler[5] In Charge of Offense Problems
Dr. Reid Hunt Advisor on Pharmacological Problems
Lt. Col. W. D. Bancroft In Charge of Editorial Work and Catalytic Research
Lt. Col. A. B. Lamb[6] In Charge of Defense Chemical Research
Dr. L. W. Jones[7] In Charge of Offense Chemical Research
Major A. C. Fieldner In Charge of Gas Mask Research
Major G. A. Richter In Charge of Pyrotechnic Research
Capt. E. K. Marshall[8] In Charge of Pharmacological Research
Dr. A. S. Loevenhart[9] In Charge of Toxicological Research
Major R. C. Tolman In Charge of Dispersoid Research
Major W. S. Rowland[10] In Charge of Small Scale Manufacture
Major B. B. Fogler[11] In Charge of Mechanical Research and Development
Captain G. A. Rankin In Charge of Explosive Research
Major Richmond Levering In Charge of Administration Section
The chief functions of the Research Division were:
1. To prepare and test compounds which might be of value in gas warfare, determining the properties of these substances and the conditions under which they might be effective in warfare.
2. To develop satisfactory methods of making such compounds as seemed promising (Small Scale).
3. To develop the best methods of utilizing these compounds.
4. To develop materials which should absorb or destroy war gases, studying their properties and determining the conditions under which they might be effective.
5. To develop satisfactory methods of making such absorbents as might seem promising.
6. To develop masks, canisters, protective clothing, etc.
7. To develop incendiaries, smokes, signals, etc., and the best methods of using the same.
F . 4.—American University Experiment Station, showing Small Scale Plants.
8. To co-operate with the manufacturing divisions in regard to difficulties arising during the operations of manufacturing war gases, absorbents, etc.
9. To co-operate with other branches of the Government, civil and military, in regard to war problems.
10. To collect and make available to the Director of the Chemical Warfare Service all information in regard to the chemistry of gas warfare.
The relation of the various sections may best be shown by outlining the general procedure used when a new toxic substance was developed.
The substance in question may have been used by the Germans or the Allies; it may have been suggested by someone outside the station; or the staff may have thought of it from a search of the
literature, from analogy or from pure inspiration. The Offense Research Section made the substance. If it was a solid it was sent to the Dispersoid Section, where methods of dispersing it were worked out. When this had been done, or, at once, if the compound was a liquid or vapor, it was sent to the Toxicological Section to be tested for toxicity, lachrymatory power, vesicant action, or other special properties. If these tests proved the compound to have a high toxicity or a peculiar physiological behavior, it was then turned over to a number of different sections.
The Offense Research Section tried to improve the method of preparation. When a satisfactory method had been found, the Chemical Production or Small Scale Manufacturing Section endeavored to make it on a large scale (50 pounds to a ton) and worked out the manufacturing difficulties. If further tests showed that the substance was valuable, the manufacture was then given to the Development Division or the Gas Offense Production Division for large scale production.
Meanwhile the Analytical Section had been working on a method for testing the purity of the material and for analyzing air mixtures, and the Gas Mask Section had run tests against it with the standard canisters. If the protection afforded did not seem sufficient, the Defense Chemical Section studied changes in the ingredients of the canister or even developed a new absorbent or mixture of absorbents to meet the emergency. If a change in the mechanical construction of the canister was necessary, this was referred to the Mechanical Research Section; this work was especially important in case the material was to be used as a toxic smoke.
The compound was also sent to the Pyrotechnic Section, which studied its behavior when fired from a shell, or, if suitable, when used in a cylinder If it proved stable on detonation, large field tests were then made by the Proving Division, in connection with the Pyrotechnic and Toxicological Sections of the Research Division, to learn the effect when shell loaded with the compound were fired from guns on a range, with animals placed suitably in or near the trenches. The Analytical Section worked out methods of detecting the gas in the field, wherever possible.
The Medical Division, working with the Toxicological and Pharmacological Sections, studied pathological details, methods of treating gassed cases, the effect of the gas on the body, and in some cases even considered other questions, such as the susceptibility of different men.
If the question of an ointment or clothing entered into the matter of protection, these were usually attacked by several Sections from different points of view.
Out of the 250 gases prepared by the Offense Chemical Research Section, very few were sufficiently valuable to pass all of these tests and thus the number of gases actually put into large scale production were less than a dozen. This had its advantages, for it made unnecessary a large number of factories and the training of men in the manufacturing details of many gases. As one British report stated, “The ultimate object of chemical warfare should be to produce two substances only; one persistent and the other nonpersistent; both should be lethal and both should be penetrants.” They might well have added that both should be instantly and powerfully lachrymatory
Since most of the work of the Research Division will be covered in detail in later chapters, only a brief summary of the principal problems will be given here.
The first and most important problem was the development of a gas mask. This was before Sections had been organized and was the work of the entire Division. After comparing the existing types of masks it was decided that the Standard Box Respirator of the British was the best one to copy. Because we were entirely new at the game that meant work on charcoal, soda-lime, and the various mechanical parts of the mask, such as the facepiece, elastics, eyepieces, mouthpiece, noseclip, hose, can, valves, etc. The story of the “first twenty thousand” is very well told by Colonel Burrell.[12]
“T F T T
“About the first of May, 1917, Major L. P. Williamson, acting as liaison officer between the
