Open main menu

Page:Popular Science Monthly Volume 65.djvu/189

This page has been proofread, but needs to be validated.
185
THE PROGRESS OF SCIENCE.

the Humphry Museum has been erected at a cost of about $170,000, mostly supplied by the benefactors fund, and a further wing for pathology and physiological chemistry is planned at a cost of about $65,000. The Humphry Museum is treated ornamentally, both inside and out. The fact that the main lecture-room is lighted entirely by artificial light, might lead us to suppose that utility had been sacrificed to architecture, but it is said that the building is well adapted to the uses of the medical school. The library is planned on a new principle, the stacks being blocked solidly on the sides, each case being movable and pulled out when wanted. This scheme seems to be ingenious; the space is nearly trebled and books are kept free from dust. It is doubtless a disadvantage to shut the books from view, but when the case is pulled out the books are more accessible than in ordinary stacks.

The buildings here mentioned are erected on land acquired by the university from Downing College, and three of them form part of an irregular quadrangle. It is hoped that a school of agriculture and an archeological museum will be added to the group within a reasonable period.

 

DEVELOPMENTS IN THE RESPIRATION CALORIMETER.

Two important developments have lately been made in this apparatus, which render it a more efficient means of determining tin' use which is made of food nutrients in the body, and extend its use tn experiments with large animals. As is well known, the apparatus as developed by Atwater and Rosa enabled the accurate determination of the carbon, nitrogen and water excreted by the subject within the respiration chamber, and the heat given off by him under different conditions of food and exercise. During the past year an alteration has been made in the apparatus by which the oxygen consumption is also determined, giving increased accuracy and furnishing data for estimating the gain or loss in protein and fat, as well as a new method of estimating the respiratory quotient. The arrangement for determining the oxygen is new and very ingenious. In adapting the apparatus to it, it has been changed from what is known as an 'open-circuit' to a 'closed-circuit' apparatus, i. e., the same air is used over and over again, the products of combustion in the body of the subject (carbon dioxide and water) being constantly removed by passing the air current through sulphuric acid and soda lime, and fresh oxygen supplied to take the place of that consumed in the respiration. The oxygen content of the air current is kept practically constant and normal. The accuracy of the modified calorimeter for measuring heat has been tested by a number of electrical check

PSM V65 D189 The armsby fries respiration calorimeter.png

Model of the Armsby-Fries Respiration Calorimeter.