MancJiester Memoirs, Vol. Ivii. (1913), No. \Vt. 5 



Guinea Pie; and Mousk Expkrim1':nts. 



With a view to finding wiiether the same relative 

 results would he obtained from the exhaled air of guinea 

 pigs and mice I endeavoured to find the method for 

 obtaining the most satisfactory' results. 



The first experiments were made b\- putting the 

 animal under a bell jar and drawing air from it through 

 strong sulphuric acitl and then over soda lime to absorb 

 the COo, but I found b\' the appliances I used, suitable 

 for delicate weighing of the soda lime tubes, that I could 

 not pass sufficient air through the bell jar to prevent a 

 high contamination of the air breathed b\ the animal, 

 and so the following was devised which enabled the 

 animal to breathe comparatively pure air during the 

 progress of the experiment. 



A specially accurate gas meter, previously tested, 

 capable of passing 12 cubic feet per hour, was connected 

 on the one side to a vacuum pump and on the other t(^ a 

 large bottle to minimise the slight vibrations from the 

 water pump. This was connected by a glass tube with two 

 bottles, each of i litre capacit)-, for receiving the breathed 

 air for anal\'sis. 



The ordinar\- air was drawn into the bell jar from 

 outside the laboratory' with glass tubes entering at the 

 top and leaving at the bottom of the bell jar, after passing 

 through a bottle of one litre capacity, in which the CO.,, 

 in the air used was determined and deducted from that 

 obtained after passing over the animal, the animal being 

 supported above the perforated glass plate on which the 

 bell jar stood b\' means of a piece of iron wire gauze. 



The air from the bell jar passed along a tube which 

 ended in a T-piece, the junction of which was provided 

 with a two-way tap, b)- which means the stream of air 

 could be diverted to the right or to the left at will. 



