CHEMICAL SCIENCE. 247 



respiration, 1st, in the whole of the twenty-four hours, with and without 

 exertion and food ; 2d, the variations from day to day, and from season to 

 season; and, 3d, the influence of some kinds of exertion. 



After a description of the apparatus employed by previous observers, he 

 describes his own apparatus and method. This consists of a spirometer to 

 measure the air inspired, capable of registering any number of cubic inches, 

 and an analytical apparatus to abstract the carbonic acid and vapor from 

 the expired air. The former is a small, dry gasmeter, of improved manu- 

 facture, and the latter consists of, 1st, a desiccator of sulphuric acid to 

 absorb the vapor; 2d, a gutta-percha box, with chambers and cells, con- 

 taining caustic potash, and offering a superficies of 700 inches, over which 

 the expired air is passed, and by which the carbonic acid is abstracted; and, 

 3d, a second desiccator to retain the vapor which the expired air had carried 

 off from the potash box. A small mask is worn, so as to prevent any air 

 entering the lungs without first passing through the spirometer, and the 

 increase in the weight of this with the connecting tube and the first desicca- 

 tor gives the amount of vapor exhaled, whilst the addition to the weight of 

 the potash box and the second desiccator gives the weight of the 'carbonic 

 acid expired. The balances employed weigh to the one-hundredth of a 

 grain, with seven pounds in the pan. By this apparatus the whole of the 

 carbonic acid was abstracted during the act of expiration, and the experi- 

 ment could be repeated every few minutes, or continued for any number of 

 hours, and be made whilst sleeping and with certain kinds of exertion. 



The amount of carbonic acid expired in the twenty-four hours was deter- 

 mined by several sets of experiments. Four of these, consisting of eight 

 experiments, were made upon four gentlemen : on the author, Professor 

 Frankland, F. R. S., Dr. Murie, and Mr. Moul, during the eighteen hours of 

 the working day. In two of them, the whole of the carbonic acid was col- 

 lected, and in two others the experiment was made during ten minutes, at 

 the commencement of each hour, and of each hour after the meals. The 

 quantity of carbonic acid varied from an average of 24.274 ounces in the 

 author to 16.43 ounces in Professor Frankland. The quantity evolved in 

 light sleep was 4.88 and 4.99 grains per minute, and scarcely awake, 5.7, 

 5.94, and 6.1 grains at different times of the night. The author estimates 

 the amount in profound sleep at 4.5 grains per minute; and the whole 

 evolved in the six hours of the night at 1950 grains. Hence the total quan- 

 tity of carbon evolved in the twenty-four hours, at rest, was, in the author, 

 7.144 ounces. The effect of walking at various speeds is then given, with 

 an estimate of the amount of exertion made by different classes of the com- 

 munity, and of the carbon which would be evolved with that exertion. 



The author then states the quantity of air inspired in the working day, 

 which varied from 583 cubic inches per minute in himself to 365 cubic inches 

 per minute in Professor Frankland; the rate of respiration, which varied in 

 different seasons as well as in different persons; the depth of inspiration, 

 from 30 cubic inches to 39.5 cubic inches; and the rate of pulsation. The 

 respirations were to the pulsations as 1 to 4.63 in the youngest, and as 1 to 

 5.72 in the oldest. One-half of the product of the respirations into the pul- 

 sations gave nearly the number of cubic inches of air inspired in some of 

 the persons, and the proportion of the carbonic acid to the air inspired 

 varied from as 1 grain to 54.7 cubic inches to as 1 grain to 58 cubic inches. 

 The variations in the carbonic acid evolved in the working day gave an 

 average maximum of 10.43 and a minimum of 6.74 grains per minute. The 



