142 On the Sulphurei of Carbon and on Flame. 



does reflect, — what is tlie use of the pigmentiim nigrum P and 

 how is the image formed by " caustic reflection " to be im- 

 pressed upon the " base of the neivc ?" It is not a tangible body: 

 and Mr. Hctrn will not, I presume, have tlie boldness to assert 

 that rays passing through a medium shall be reflected at a 

 certain point, without any alteration in the density of that me- 

 dium, ^'et were all his positions correct, the vitreous Hjamour 

 must diminish the image, which will be considerably larger than 

 the base of the nerve, and reflect it afterwards — a power which no 

 one in his senses will allow it. What then would be the conse- 

 quence of such reflection? Why, the rays would decussate each 

 other in every possible angle; and instead of one we should have 

 a hundred images, not one of which would approach the base 

 of the nerve. 



If these statements are true, — and I don't see how they can be 

 disproved, as they are little more than a collection of facts, — 

 What foundation has Mr. Horn for his theory ? 



Yours respectfully, 

 London, Feb. 18, 1817. " J. Q. R. 



XXXV. On the Sulphuret of Carbon and on Flame, &c. By 

 J. Murray, Esq. 



To Mr. Tilloch. 



Sir, — In an early number of the " Annals of Philosophy," I 

 pointed out some phienomena attendant on the great t-eduction 

 of temperature by the evaporation of sulphuret oj" carbon, I 

 find that if a few drops of this fluid be passed into a vessel of 

 oxygen, it will explode vhdenthi on application of an ignited 

 taper to the orifice. Sulphuret of carbon burns, when pre- 

 viously ignited in a medium of chlorine,but does not inflame spon- 

 taneously therein ; when burning in contact with the atmosphere 

 it exhibits an exaltation of temperature exceeding in intensity 

 that of any other unexplosive flame, I have yet examined. Steel 

 wire oi l-30th inch diameter burnt almost as vividly in this 

 flame as in oxygen. Even a ivatch-spring fused with scintilla- 

 tion, and fine fibres of amianthus and platinum wire readily 

 melted. Of the flar.ies exhibited by combined hydrogen, those of 

 hydrozincicgas and of boretted hydrogen appear to be the most 

 intense; for in these, steel wire fuses vividly, and fine fibres of 

 amianthus melt. 



The blueish flames of alcohol, ether, &c. exhibit a 7'o.?e-colour 

 by the introduction of metals, charcoal, &;c. and in the green 

 flame of boretted hydrogen, &c. evolve a. yellow colour. Scarlet, 

 rose, and carmine, are the colours most generally produced with 



this 



