126 



point of water ; and also a higher temperatui-e, ranging from 60° to 

 70° ; but not above 83°, a temperature which in the single instance 

 tried was almost immediately fatal to it. 



In conclusion the author briefly adverts to the application of the 

 results obtained to the breeding and transporting of the fish, adding 

 some remarks on the quality of water essential to its healthy condition 

 and preservation. 



Monday^ bth April 1852. 



Right Reverend BISHOP TERROT, Vice-President, in 

 the Chair. 



The following Communications were read : — ■ 



1. On a modification of the Process for the determination 

 of Nitrogen in Organic Compounds. By Alexander 

 Kemp, Esq. 



Two methods are at present followed by chemists for the analysis 

 of organic bodies containing nitrogen. In the first of these the 

 nitrogen is directly separated from the substance, and measured in a 

 pure state ; while in the second method it is converted into ammonia, 

 collected and weighed, its amount being calculated from the known 

 composition of this latter substance. 



In accordance with the first-named mode of proceeding, the sub- 

 stance is burned at a high temperatui-e, in contact with oxide of 

 copper, chromate of lead, or some other body capable of yielding 

 oxygen, when the carbon of the organic substance becomes converted 

 into carbonic acid, and its hydrogen into water, while all the nitro- 

 gen is given off in a free state. Two methods may now be adopted 

 for ascertaining its quantity. In that recommended by M. Dumas, 

 the evolved gases are collected in a series of graduated glass tubes, 

 previously filled with mercury, and containing some potash ley in 

 the upper part, which serves to absorb the carbonic acid, leaving the 

 nitrotren, which may then be measured, and its weight calculated 

 from its known volume and density, due allowance being made for 

 the temperature, pressure, and the presence of aqueous vapour. 



According to Liebig, the same object may be more easily and 

 rapidly attained, by comparing the volume of the carbonic acid gas 

 produced with that of the nitrogen given out in the operation. This 



