or FOODS UPON THE EESPIEATION. 
717 
similar and normal conditions. We sat down at least a quarter of an hour before taking 
the fii’st observation, or that which showed the state of the system before the substance 
under inquhy was taken, and which was the basal state with which the subsequent effects 
of the substance were compared, and upon the accuracy of which the truthfulness of the 
results mainly depended. We then ate the substance in question, and in from 3 to 
10 minutes afterwards made our first inquiry into its effects ; and repeated the inquiry 
every 12 or 15 minutes (as frequently as we could complete each experiment), until the 
maximum effect had passed ; the same conditions as to posture and quietude being main- 
tamed unbroken throughout the whole inquiry. We did not continue the experiment 
beyond our usual breakfast hour ; for, in accordance with a statement made in my former 
paper, we found that an increase in the respiratory phenomena occurred at the meal 
hour before any food had been taken. Hence it was neither necessary nor desirable to 
continue the inquiry much beyond two hours. Each of these experiments lasted five 
minutes, but in several of them the inquhy was continuous, and the whole of the 
carbonic acid evolved during the action of the substance was collected. 
In recording the results, we made use of the total quantities ; but in abstracting them 
for the purposes of this communication, I have compared them with the basis quantity, 
and have given the amount of increase or decrease only. This was necessary, both on 
account of the observation made above, and because the total quantities varied with the 
season. 
The apparatus employed was that described in my previous paper *, consisting of an 
instiument to measure the quantity of inspired air, and an analytical apparatus to abstract 
the vapour and carbonic acid from the whole of the expired air. The force of inspiration 
and expiration was in a few instances determined by a bent tube with a column of water 
attached to the mask ; and the temperature of the expired air was determined by the aid 
of a smaU thermometer inserted at right angles into a box-wood tube, inch in length, 
and protected by valves, as described in my paper published in the ‘ Proceedings ’ of 
the Society for 1857. The temperature with the wet and dry bulb, and the barometric- 
pi essuie, were recorded, as was also the state of the weather. 
The foods which have been the subjects of inquiry are very numerous, and of the 
finest quality ; and some of them, as tea, sugar, milk, and alcohols, were subjected to 
very numerous and varied experiments. As the results have shown that it would be 
inconvenient to arrange them solely according to their chemical constitution, I purpose 
to describe them under the following heads : 
1. The Starch Series, viz. arrowroot, arrowroot and butter, arrowroot and sugar, com- 
meicial starch, wheat starch, gluten, bread, oatmeal, rice, rice and butter, 
potato, gum. 
-j. The Fat Series, viz. butter, olive oil, cod-liver oil. 
3. Sugars, wz. cane-sugar, cane-sugar and butter, cane-sugar with acids and alkalies, 
grape-sugar, milk-sugar. 
* Page 682 of this volume. 
