660 APPENDIX. 



cessively. Each burnt brilliantly, and a good deal of gas was 

 evolved which passed into the mercurial trough. This process 

 was continued till all the common air was driven out of the tube* 

 and it was filled with nothing but the gas extricated by the com- 

 bustion of the balls. A number of the balls (first accurately 

 weighed) were then dropped into the tube and deflagrated, and 

 the gas evolved collected in a graduated jar. Then another and 

 another jar was filled in exactly the same manner, each contain- 

 ing the gas evolved by the combustion of nine or ten grains of 

 the substance to be analyzed. The bulk of the gas in the first 

 jar being measured it was subjected to analysis, and consisted of 

 a mixture of oxygen, carbonic acid, and azotic gas, (if the sub- 

 stance under examination contained that principle.) The bulk 

 of the carbonic acid was determined by absorbing it by means of 

 caustic potash, and that of the oxygen by mixing 100 volumes of 

 it with 40 of hydrogen, and passing an electric spark through it. 

 The diminution of volume determined the purity of the oxygen 

 and the presence or absence of azotic gas, carbonic oxide, &c. 

 The quantity of oxygen gas evolved from the weight of chlorate 

 of potash used being known, and the quantity collected and in 

 the state of carbonic acid gas being subtracted from it, the re- 

 mainder indicated the volume of oxygen gas which went to the 

 formation of water. The carbonic acid, hydrogen, and azote 

 thus evolved by the combustion of the substance under analysis 

 being known, and the amount of these being added and subtract- 

 ed from the weight of the substance subjected to analysis, the re- 

 mainder gave the quantity of oxygen which the substance under 

 analysis contained. 



In this way they analyzed fifteen vegetable substances, none of 

 which contained azote, and four animal substances, each contain- 

 ing azote as a constituent 



The process of Gay-Lussac and Thenard was considerably 

 improved by Berzelius in 1814.* He adopted the chlorate of 

 potash, which he mixed with the substance to be analyzed. The 

 mixture he put into a stout glass tube, shut at one end. The 

 open end was luted to a small receiver, which terminated in a 

 long glass tube filled with dry chloride of calcium. To the end 

 of this tube was luted a bent tube, plunging into a mercurial 

 trough with a glass jar filled with mercury to receive the gas 

 evolved. After the process was over the receiver and chloride 



* Annals of Philosophy, 401. 



