NATURAL PHILOSOPHY. 171 



smallest quantity of chlorine produces tlie yellow ray by the light, 

 and the greatest quantity the orange ray ; or in other words, with a 

 given quantity of chlorine, the light will develop all the colors, accord- 

 ing to the intensity of the luminous rays. 



To sum up, the chlorine, alone, produces only flames of a weak 

 color compared with those produced by a chloride of copper ; and it 

 is the same with the hello-chromatic colors, that is to say, those pro- 

 duced by the light on a sensitive plate. It is therefore very remarka- 

 ble that the same relations exist between colored flames and images 

 colored by the light, since, according to the quantity of chlorine that 

 I place in my bath to prepare a silver plate, I obtain one or the other 

 predominant color. The others will be scarcely observable ; only one, 

 or at the most, two, will have any strength. I have found only two 

 metals that afford flames of different colors when combined with chlo- 

 rine ; they are copper and nickel. This last, however, gives colors by 

 no means vivid, compared with those of copper. I have not been able 

 to get a change of color from the chloride of strontium, the chloride 

 of sodium, the bi-chloride of potassium and uranium, or bromic acid, 

 by increasing the quantity of chloride or the intensity of the heat. 

 It may be said that this theory en the obtaining of colored images by 

 the light differs from that which I gave in my first memoir ; yet it is 

 clear that the basis is still the same, and that what I attributed to the 

 color given to the flame by the base of the chloride added to the sub- 

 stance in combustion, was true only in regard to the quantity of chlo- 

 rine or chloride that I employed to form the bath in which I prepared 

 the silver plate. 



COLORS MOST FREQUENTLY HIT DURING BATTLE. 



IT would appear, from numerous observations, that soldiers are hit 

 during battle according to the color of their dress, in the following 

 order : Red is the most fatal color ; the least fatal, Austrian grey. 

 The proportions are, Red 12; Rifle Green 7; Brown 6; Austrian 

 Bluish-Grey 5. Jameson's Journal. 



ACCOUNT OF A ROCK CRYSTAL LENS AND DECOMPOSED GLASS 



FOUND IN NINEVAH. 



SIR DAVID BREWSTER at the last meeting of the British Asso- 

 ciation, said that he had to bring before the meeting, an object of 

 so incredible a nature that nothing short of the strongest evidence was 

 necessary to render the statement at all probable : it was no less than 

 the finding in the treasure house at Ninevah of a rock crystal lens, 

 where it had for centuries lain entombed in the ruins of that once 

 magnificent city. It was found in company with several bronzes and 

 other objects of value. He had examined the lens with the greatest 

 care and taken its several measurements. It was not entirely circular 

 in its aperture, being 1 6-10ths inches in its longer diameter and 1 

 4-10ths inches in its shorter. Its general form was that of a piano- 



