IN DISEASES. 381 



bodily weight, and the age and constitution of the individual. All 

 the experiments were made in the middle of the day between 10 and 

 1 o'clock, and the patient was in no case suffered to remain more 

 than half an hour in the apparatus. The observations were made 

 principally between the months of September and December. 



Hannover instituted experiments on the respiration of five 

 persons suffering from pulmonary tuberculosis ; the tubercles being 

 in part already softened and suppurating. The absolute amount 

 of carbonic acid generally increases with the number of the respi- 

 rations, while the relative amount (that which is contained in a 

 definite volume of air) diminishes. The other experiments made 

 by Hannover on the excretion of carbonic acid in some other 

 morbid conditions, are too disconnected to admit of our deriving 

 any definite results from them. 



Doyere repeatedly examined^ the air expired by a young girl 

 who had cholera, and continued his observations till the death of 

 the patient; he found that the excretion of carbonic acid was 

 generally much diminished in this disease, and that this excretion 

 was augmented as soon as the general condition of the patient 

 improved. 



Malcolm instituted a more exact series of experiments, ac- 

 cording to Prout's method, on this relation in typhus, in which he, 

 of course, determined only the relative quantity of carbonic acid 

 in the expired air. This observer found that in nineteen cases of 

 mild typhus the quantity of carbonic acid contained in 100 volumes 

 of the expired air, varied between 1*18 and 4' 15 ; the mean of all 

 these observations gave the number 2'492-g-, but this quantity fell 

 to 2'232g- in seven more severe cases of typhus. Prout gives 

 3*96 g- as the mean number for persons in health; the relative 

 amount of carbonic acid in the expirations is therefore very con- 

 siderably diminished in typhus. The amount of carbonic acid in 

 the air cannot be brought into any definite proportion either to 

 the number of the respirations or of the pulsations. 



Here again we perceive the great deficiencies of pathological 

 chemistry, which does not even supply us with the necessary 

 materials for establishing a system. On the other hand, it must 

 be admitted that the charge of inapplicability to medical practice, 

 which has been advanced against this section of physiological 

 chemistry, is less just in the case of the respiration than in the 

 theory of digestion (seep. 308). Until recently, the determination 

 of the respirations, and of the contractions of the heart in cases 

 of disease, were little more than mere symbols, which nothing but 



