IN POPULAR CHEMISTRY. Si) 



13. Why are matches poisonous? What is the anti- 

 dote ? 



Because of the phosphorus in the match. Turpentine has 

 been proposed as a remedy, but is not known to be reliable. 



14. Will the burning phosphorus ignite the wood of the 

 match ? 



It does not give off enough heat in its oxidation to raise the 

 temperature of the wood to the igniting point. Some substance 

 of low kindling point, such as sulphur, or which contains a 

 large amount of O, such as KC1O ;J , is added to produce violent 

 oxidation and kindle the wood. 



15. What principle is illustrated in the ignition of a 

 match by friction ? 



The conversion of motion into heat. 



l(t. How much H Z O would be required to dissolve a 

 pound of KNO Z ? 



3i Ibs. of cold water, or i Ib. of hot water. 



17. What causes the bad odor after the discharge of a 

 gun ? 



The potassium sulphide gradually gives up its S to form 



combined with, but one unit of base. On the other hand, its teeth must 

 be harder than its hardest bones, and a new demaiid is made on the lirae- 

 phosphates to associate themselves with other lime-salts (especially fluoride 

 of calcium), to form the cutting edges and grinding faces of the incisors 

 and molars. All the while, also, the blood must be kept alkaline, that oxi- 

 dation of the tissues may be promoted, and albumen retained in solution ; 

 and yet it must not be too alkaline, or tissues and albumen will both be 

 destroyed, and the carbonic acid developed at the systemic capillaries 

 will not be exchanged for oxygen when the blood is exposed to that gas 

 at the lungs. So phosphoric acid provides a salt containing two units 

 of soda and one of water, which is sufficiently alkaline to promote oxida- 

 tion, dissolve albumen, and absorb carbonic acid, and yet holds the latter 

 so loosely, that it instantly exchanges it for oxygen when it encounters 

 that gas in the piilmonary capillaries. Again, the flesh juice must be kept 

 acid (perhaps in opposition to the alkaline blood, as affecting the trans- 

 mission of the electric currents which traverse the tissues), and phosphoric 

 acid provides a salt, containing two units of water and one of potash, 

 which secures the requisite acidity. 11 DR. G. WILSON, Edinburgh Essays, 1856. 



