298 BUNSEN ON THE CACODYL SERIES. 
methods. The first analysis was made with chromate of lead, 
and the second with oxide of copper. 
I. 0°5160 grm. of substance yielded 0°5285 grm. carbonic acid, 
and 0°2123 grm. water. 
II. 0°3870 grm. of substance yielded 0°388 grm. carbonic acid, 
and 0°1625 grm. water. 
The experiments which were made to determine the azote all 
failed, as the proportion to the carbon is so very small, and the 
substance undergoes such an unequal combustion. The first 
tubes indicated the relation of the azote to the carbon as 1: 6°7, 
the intermediate ones as 1:11, and the last as 1: 5°3. I there- 
fore employed a new method which is much simpler, and in 
which all the errors that more or less accompany the old plans 
may be easily avoided. As I intend to make this method the 
subject of a separate communication, I will not here enter into 
particulars, further than to say, that not more than from 0°03 to 
0°08 grm. of substance with 2 grms. of oxide of copper, and a few 
copper turnings, are quite sufficient. These are placed in a 
small glass tube filled with hydrogen, then exhausted by the air- 
pump, and finally hermetically sealed. This tube with the mix- 
ture is then exposed for half an hour to a gentle red heat. The 
tube is fixed in an apparatus which prevents its bursting by 
the pressure of the gas, which amounts to 8 or 10 atmospheres, or 
cracking on cooling. It is placed on cooling under mercury, and 
the contents emptied into a graduated receiver, when the relative 
proportion of carbonic acid and azote are determined in the usual 
way by potash. The following is the result of the experiment. 
Gas volume at commencement. . . . . 266°0C.C. 
Barometer .. . oe 6 a!) OFSSR metre: 
Mercurial column dhove the evel of the cistern 0°2850 
Temperature . . oe eS eeemtre. 
Tension of steam at this felt pelt - «- OOl2 metre: 
Volume after absorption of carbonic acid . 46:2 C. C. 
Barometer . .. . 2. Sse mettre: 
Mercurial column above the He of the cistern 0°3558_... 
Temperature. . . oe 5 
The relation of the enue acid to the azote is therefore as 
6: 1:040. 
The experiment was repeated as follows :— 
Volume of gas at commencement . .. . . 361°7 
Barometers.) iw fn et 2 Jo eee 
