34 CHEMISTRY. 



rus in oxygen, some of the gas disappeared, the phosphorus increased 

 in weight, and the increase of the latter was precisely equal to the 

 loss of the former. Lavoisier, however, went too far in supposing 

 that oxygen was the sole supporter of combustion ; since it has been 

 proved that other gases, as chlorine, cyanogen, &c., will also sup- 

 port it. He also accounted for the intense light and heat produced 

 during combustion, on the principle of latent heat; but in this he 

 was subsequently proved to be incorrect. No certain explanation of 

 these phenomena have indeed been givt?n, though they have been 

 attributed to chemical action by some, and to electricity by others ; this 

 latter view is adopted by Berzelius. 



All combustibles do not emit an equal amount of heat on being 

 burned. 



HYDROGEN. 



Exists abundantly in nature ; constitutes one-ninth by weight, of 

 water, and two-thirds by volume ; named from the Greek words sig- 

 nifying to generate water. Prepared always by decomposing water, 

 which may be effected either by bringing steam in contact with red 

 hot iron, which then combines with the oxygen of the water, liberat- 

 ing pure hydrogen ; or by the action of dilute sulphuric acid on 

 pieces of zinc or iron; in this case the water of the sulphuric acid 

 yields its oxygen to the zinc, and its hydrogen escapes : the oxide of 

 zinc at the same time unites with the acid to form the sulphate of 

 zinc, thus : — 



Water \ "7^^°?^^ ^'^^' 



} Oxygen . 



Zinc • ■ oxide of zinc ^ Sulphate of 



Sulphuric acid ■ f oxide of zinc. 



Prop. — Colourless, inodorous, tasteless ; the lightest body in na- 

 ture, sp. gr. 0-06896; 100 cubic inches only weigh 2*137 grs. It 

 cannot be compressed into a liquid ; a non-supporter of combustion 

 and respiration, though its latter property arises, not from any noxious 

 property of the gas, but only from an absence of oxygen ; it is highly 

 inflammable, burning with a pale bluish flame ; when mixed with a 

 due proportion of oxygen, (2 measures of hydrogen to 1 of oxygen,) 

 it explodes violently, either by a heated body, or the electric spark, 

 giving rise to the formation of water. 



Spongy platinum is instantly made red hot by a jet of hydrogen, 

 which, in its turn, is then inflamed ; — a mixture of hydrogen and 

 oxygen, will burn slowly without explosion, when the temperature is 

 raised a little above that of boiling mercury. The burning of hydro- 

 gen with oxygen is accompanied with the evolution of a great amount 

 of heat ; on this principle the oxy-hydrogen blowpipe is constructed, 

 consisting of an apparatus by which a mixture of hydrogen and 

 oxygen is made to burn from a jet, care being taken to guard against 

 the danger of explosion, by means of Hemming's safety tube ; the 



