1818.] the Commencement of the Year 1817. Parti. 5 



When azotic gas is mixed with rarified air instead of carbonic 

 acid gas, the diminution of heat which the animal undergoes is 

 still considerable, though much less than in the former case. It 

 is least of all when the animal is made to respire rarified air. 



The temperature of the animal was determined in these cases 

 by introducing the bulb of a thermometer into a small orifice cut 

 in the skin of the breast. In all probability this diminution of 

 heat was only superficial. We can hardly conceive the possibi- 

 lity of the temperature of the heart and blood being reduced 

 25° without destroying the life of the animal. M. Legallois 

 observed that dogs and cats consume a much greater proportion 

 of oxygen, compared to their weight, than rabbits. It would 

 throw considerable light on this obscure subject if it could be 

 determined whether the waste of animal heat in the first of these 

 animals be greater than in rabbits. This is an investigation 

 which M. Legallois proposed to undertake. — (Ann. de Chim. et 

 Phys. iv. 1, 113.) 



5. Hydrogen Gas Lamp. — M. Gay-Lussac, who has a parti- 

 cular genius for contriving simple and useful pieces of apparatus, 

 has suggested a little instrument which may be useful in labora- 

 tories, either as a lamp or as a reservoir, to supply small quanti- 

 ties- of hydrogen gas for the purposes of experiment. It consists 

 of a Woulfe's bottle with three mouths. Into the central mouth 

 is luted a glass tube open below and sinking nearly to the 

 bottom of the bottle ; the upper part of this tube, or the outside 

 of the bottle, is blown into a ball of a capacity which ought not 

 to be less than that of the bottle, and there is a small hole in the 

 upper part of this ball so as to admit freely the atmospheric air ; 

 to another of the mouths of the Woulfe's bottle is ground a glass 

 stopper so as to be perfectly air-tight, and to the'extremity of the 

 stopper is attached a cylinder of zinc, which may sink about two 

 thirds of the length of the bottle ; to the third mouth of the 

 Woulfe's bottle is luted a glass tube, which may be fitted with a 

 stop-cock, and turned conveniently for burning as a lamp, or for 

 supplying hydrogen gas. The bottle is to be filled with dilute 

 sulphuric acid, and the glass tube and ball, the stopper with the 

 zinc cylinder, are to be fixed in their places. The acid will 

 immediately begin to act on the zinc, and to generate hydrogen 

 gas. This gas will accumulate in the upper part of the bottle, 

 and by its elasticity will force the diluted acid into the glass 

 ball till the surface of the liquid in the bottle gets below the 

 cylinder of zinc : the formation of gas will then stop. When 

 the stop-cock is opened, the weight of the liquid in the ball 

 will force the hydrogen gas to issue through the tube ; and it may 

 be either set on fire and burned as a lamp, or collected in a pneu- 

 matic trough for the purposes of experiment. When the gas is 

 sufficiently wasted, the sulphuric acid descends into the bottle, 

 and gradually rises till it comes in contact with the zinc : new 



