416 Mr. Trull 07i the Effects of Light and Air in restoring 



avoid the effects of heat. In this state it possessed the fol- 

 lowing characters; it is a white powder, destitute of taste 

 and smell, soluble in water, insoluble in alcohol and aether. 

 When subjected to analysis in the usual way, the following 

 results were obtained : 



I. ''i'i'Sfi grms. gave '618 grms. CO.^ and •24;4<5 grms. HO. 

 II. •3625 grms. „ '6365 „ „ and -2505 „ „ 



The relation of the carbon and azote was as 3 C to 1 A. 

 From these results we have 



I. II. 



Carbon 49*025 48-555 



Azote 18-910 18-742 



Hydrogen 7-788 7'677 



Oxygen 24-272 25:026 



100-000 100-000 



The fact of the existence of the substance operated on in the 

 almonds appears to be established by its acting on amygdalin in 

 the same manner as the milk of almonds alluded to in the com- 

 mencement of the paper. After numerous trials with various 

 reagents, its most distinguishing character was elicited by the 

 phsenomena exhibited when boiled with barytes. During 

 the whole of the boiling, which was continued above six hours, 

 ammonia was slowly and continuously disengaged. Through 

 the solution a current of carbonic acid gas was passed, and the 

 whole filtered ; the clear solution was evaporated to dryness, 

 and the residual salt, which contained a large quantity of 

 barytes, possessed a strongly bitter taste; thus leading to the 

 conclusion that emulsin is an amide ; and that the salt formed 

 by the action of barytes is a compound of barytes with an 

 acid which we propose to term emulsic acid. The relations 

 of emulsin to albumen, fibrin, and casein, &c. will form matter 

 for subsequent investigation. 



LXII. On the Effects of Light and Air in restoring the faded 

 Colours of the Raphael Tapestries. By Mr. Trull; com- 

 immicated by Michael Faraday, Esq.^ D.C.L., F.R.S. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, April 21,1 839. 



OU probably remember an exhibition in July last of cer- 

 tain Raphael Tapestries in the Haymarket, and the 

 extraordinary effect the exposure to light and air had had in 

 restoring and altering colours which had faded during cen- 



Y 



