Ma. I will, my dear! Gun powder is made of nitre', sul- , phur', and charcoal. The proportions of these are very unequal', by far the largest part is nitre'. When a gun is charged with powder and bail, it is dischar. ged by pulling the trigger'. This causes the lint which is fixed in the lock, to strike against the steel pan', and produce sparks of fire.' The fire instantly catches the sulphur'; this again inflames the charcoal'; then the nitre mixed with them becomes strongly heated and the enclosed air expanded'; this forces the charge from the mouth of the musket with amazing velocity and a thundering noise'. The whole is the work of a moment. Jane. I think I understand you'. But the cannon which we saw in the Park', was let off by a match or lighted torch'. They are too large for locks' I suppose'. Pray what is charcoal? Ma. It is wood heated to a coal, or charcoal). The wood is cut to a proper length', then put up in stacks and covered with turf, coated with a plaster of thick mud'. A few air holes are left, in which fire is placed'; and when once on fire, these are partially stopped', and the wood left to roast'. Jane. If no air was admitted the fire would not burn': this we daily prove by our common fires'. Ma. At the end of two or three days', the wood becomes charred'; the air holes are then completely closed' and the fire goes out'. ARITHMETIC.--LESSON 35. Subtraction of mixed numbers. Rule. Place the given terms as in whole numbers, and borrow when necessary, and carry for the number that equals the denominator. (1) 163–72=91 Ans. 91+72=163 Proof. 167-73=82. Ans. $3+7=163 Proof. 32--26=54 Ans. 5+263=324 Proof. (4) 12-5= (5) 42-3117= (6) 354-1312= 17) 1515-716= is) 162166-9576 (9) 267119-199142= GRAMMAR.--LESSON 36. Exercises in Parsing. Obs. Who, as a relative, is applied to persons only, unless in the possessive case; then it may apply to things. Which, as a relative, is applied to the brute creation, and to inanimate objects. That, as a relative, inay be applied either to persons or things when it becomes necessary to avoid the repetition of who, or which. As, when used in connexion after such, takes the place of a relative pronoun, in preference to who, which, or that. 169 0 16 1 Jane. Are not the fumes of charcoal', when burning', very unhealthy'? Mu. They are', my child', and should never be admitted in10 sleeping apartments! Many people have lost their lives by this careless use of it'. Jane. And now', ma', what is sulphurl? Ma. Sulphur is a simple, inflammable substance"; that is', it casily takes fire! It emits a light, blue flame', and a most offensive and suffocating smell. It is found in the earth', united', generally, to some other substances'; but near volcanoes', it has been found in a pure state! Mary. Is it used for no other purpose than in making gunpowder ? Mui. O yes', my child', it is used for bleaching straw, workcd into hats'; and also for medicine'.. Jane. Yes'; and it is very unpleasant to take'. Ma. All medicines', my child', are rather unpalatable', and generally very powerful'. Were they pleasant', we might be induced to use them to our destruction'. ARITHMETIC.-LESSON 39. Multiplication of Mixed Numbers. . RULE 1. When only one of the given terms is a mixed number, then multiply by the whole number, and take parts of the multiplicand for the fractions; the sum of these and the product will be the answer. Thus: (1) 138 X 6 . 6 · 9312 (2) 656 X 16 =10710. (3) 326 X 1241341405) Rule 2. When both the given terms are mixed numbers, first multiply the whole number by the denominator of the fractions, and add in the numerator; then multiply the factors into each other, and divide the product, by the product of the two donominators. 157 X 145 = Thus: 16X8+3=131, and 14X8+5=117. Then 131X 117=15327 product. SXS=64, divisor. Finally 15327:61=2393! Answer. |