148 Proceedings of Philosophical Societies, [Feb. 



process is the muriatic acid, and that the saline matters consist 

 chiefly of the alkaline muriates. 



The method adopted by the author to prove this, was to digest 

 the contents of the stomach of a rabbit, or other animal, in dis- 

 tilled water as long as they imparted any thing to that fluid. 

 The solution was then divided into four equal portions. The 

 first of these was evaporated to dryness in its natural state, and 

 the residuum burnt, by which means the muriatic acid in union 

 with z. fixed alkali was ascertained. Another portion was super- 

 saturated with potash, evaporated to dryness, and burnt as before, 

 and thus the total quantity of muriatic acid present determined. 

 A third portion was exactly neutralized with a solution of potash 

 of known strength, which gave the proportion of free acid pre- 

 sent. A fourth portion was reserved for miscellaneous ex- 

 periments. From the results thus obtained, checked by others, 

 the author was enabled to ascertain the proportion of muriatic 

 acid present, whether in union with a fixed or volatile alkali, 

 or in an unsaturated state ; and the quantity in the latter state 

 was always found to be considerable, and in some instances 

 greater than the quantity in combination. Dr. Prout obtained 

 similar results in different animals, as well as in the human sub- 

 ject, and in one instance, from 20 ounces of fluid ejected from 

 the human stomach, in a severe derangement of that organ, he 

 found upwards of half a dram of muriatic acid of specific gravity 

 1-160. 



The reading was also commenced of a paper, entitled, " An 

 Inquiry respecting the supposed Heating Effect beyond the Red 

 End of the Spectrum; by Baden Powell, MA. of Oriel College, 

 Oxford: " communicated by J. G. Children, Esq. FRS. 



Dec. 18. — The reading of Mr. Powell's Inquiry was con- 

 cluded. 



The primary object was to ascertain whether the explanation 

 of the invisible heating rays suggested by Prof. Leslie, viz. that 

 the effect was owing to a concentration of secondary light 

 reflected from the clouds, refracted to a position just without the 

 red rays, was correct or not. — (Inquiry into the Nature and Pro- 

 pagation of Heat, p. 457, and note 45.) 



The experiment was tried with a differential thermometer, having 

 the sentient bulb blackened with Indian ink. The prism was 

 placed in situations most favourable to such an effect, and in 

 various inclinations ; but the effect exterior to the red rays was 

 never more than 3°, while in the extreme visible red, it was often 

 from 16° to 25°. 



The effect of altering the coating was next tried; and on 

 covering the bulb with thin yellowish-brown silk, it stood in the 

 extreme red rays at 7° ; half an inch beyond, at 7° ; while, when 

 merely blackened, it stood in the red at 12°; half an inch 

 beyond, at 2°. 



It appears then that the exterior heating effect is not produced 



