CHEMISTRY. 



109 



readv saved by this means during the past year up- 

 ward* of 1,000 tons of coal. The amount of pyrites, 

 arid also of nitre used, is also reduced for the pro- 

 duction of the same amount of acid. 



A New Coloring- Matter. Eosine is the name 

 given to a new coloring-matter, first produced 

 commercially by Caro, at the Baden Aniline- 

 Works, and by him introduced to the trade. 

 Baeyer, several years ago, showed that when 

 phthalic oxide obtained by the oxidation of 

 naphthaline, and resorcine, are heated together, 

 a highly-fluorescent substance, fluorescein, is 

 formed, from which, by treatment with reduc- 

 ing agents, fluorescine, a colorless base, is de- 

 rived. By treatment with bromine, and com- 

 bination with potash, the new dye-stuff is ob- 

 tained. Its name is derived from a Greek 

 word signifying the red of the morning dawn. 

 Hofrnann has examined it, and finds it to pos- 

 sess the following properties: 



It has a beautiful red color, recalling that of ro- 

 saniline, but inclining more to garnet-red. The 



Rowder here and there shows facets with a metallic 

 istre. It is soluble in water and alcohol, and its 

 solutions are strongly fluorescent. It contains no 

 nitrogen, and evolves hydrogen bromide when heat- 

 ed, leaving a residue containing potassium bromide. 

 Distilled with zinc-dust it afforded benzole. Its 

 aqueous solution, treated with an acid, threw down 

 a brick- red powder, which, recrystallized from gla- 

 cial acetic acid, appeared as yellow prisms, having 

 the composition C 2 oH 8 Br 4 5 ; a formula confirmed 

 by the analysis of the barium salt, CaoUeB^BaOs. 

 The solutions of this substance in alcohol and water 

 appear of a delicate rose-color in transmitted light, 

 and of a pure yellow color in reflected light. The 

 shades produced on wool and silk resemble cochi- 

 neal. On silk fibre the dye retains its remarkable 

 dichroism showing red or yellow according to the 

 direction in which it is viewed. 



Detection of Lead in the Tin Lining of 

 Vessels. In a paper read before the French 

 Academy (March 29, 1875), M. Fordos gives 

 a new and rapid process for detecting lead in 

 the tin lining of vessels. He says : 



Place, with a tube plunged in pure nitric acid, a 

 slight layer of acid upon any part of the tinning, se- 

 lecting by preference the thickest parts. Both 

 metals are attacked, forming stannic oxide and ni- 

 trate of lead. After a few minutes, heat slightly to 

 expel the last traces of acid, and allow to cool ; then 

 touch the pulverulent spot produced by the acid 

 with a tube dipped in a solution five parts of iodide 

 of potassium in one hundred of water. The iodide 

 has no action upon the oxide of tin, but with the 

 nitrate of lead it reacts, forming yellow iodide of 

 lead, and showing the presence of even a small 

 quantity of this metal. The surface of the tinning 

 must be carefully cleansed before applying the ni- 

 tric acid, and the acid should not penetrate to the 

 iron or copper which forms the body of the vessel, 

 as the reaction might thus be complicated. 



Action of Light on Silver Salts. In a pa- 

 per on "The Action of the Less Eefrangible 

 Rays of Light on Silver Iodide and Silver Bro- 

 mide," published in the American Journal of 

 Science and Arts for April, 1875, M. Carey 

 Lea gives an account of some investigations of 

 his own which go to establish the following 

 propositions, viz. : 



1. That these two salts of silver are sensitive to 



all the visible rays of the spectrum ; 2. That silver 

 iodide is more sensitive than silver bromide to all 

 the less refrangible rays, and also to white light ; 3. 

 That^the sensitiveness of the bromide to the green 

 rays is materially increased by the presence of free 

 silver nitrate ; 4. That bromide and iodide of silver 

 together are more sensitive to both the green and. 

 the red rays, and probably to all the rays, than either 

 the bromide or iodide separately ; 5. That, contrary 

 to Becquerel's theory, there do not exist any rays 

 with a special exciting or special continuing power, 

 but that all the colored rays are capable both of com- 

 mencing and continuing the impression on silver 

 iodide and bromide. 



In the same journal for the previous month, 

 Mr. Lea, in opposition to the views of Vogel, 

 maintains that the power of heightening the 

 sensitiveness of silver bromide and silver 

 iodide to particular rays is in no way con- 

 nected with the color of the sensitizing body ; 

 indeed, that perfectly colorless bodies, or bodies 

 having very pale neutral colors, may also exer- 

 cise the functions of heightening sensitiveness 

 to particular colored rays. 



Action of Light on Cane-Sugar. The re- 

 sults of some experiments by Kreusler, made 

 to test the assertion of Raoult, that pure cane- 

 sugar in aqueous solution, both air and fer- 

 ments being completely absent, underwent an 

 inversion solely under the influence of light, 

 are thus described in the same journal : 



While Kaoult used only a solution containing ten 



f -amines of white sugar to fifty grammes of water, 

 reusler employed solutions of various strengths. 

 These were sealed up in glass tubes, after careful ex- 

 haustion, and, with the exception of one, were ex- 

 posed, in a window facing the southeast, to the direct 

 sunlight for eleven months ; more than twice the time 

 given by Eaoult. On opening the tubes, they still 

 showed a good vacuum, and the liquid was clear and 

 free from microscopic vegetation of any sort. But 

 when tested with Fehling's solution, neither the 

 liquid exposed to the light nor that preserved in 

 darkness gave the slightest reaction. Upon repeat- 

 ing the experiment, however, taking care to intro- 

 duce a small quantity of air into the tubes before 

 sealing, organic ferments were found present, and 

 the liquid reduced strongly the copper test ; that ex- 

 posed to light being the more active. The author 

 believes, therefore, that an imperfect exhaustion in 

 Kaoult's tubes was the cause of the results he de- 

 scribes. 



New Test for the Detection of Prussic Acid. 

 A new and exceedingly delicate test for prus- 

 sic acid, devised by M. Carey Lea, of Philadel- 

 phia, is thus described by him in the American 

 Journal of Science and Arts : 



If a little pure protosalt of iron (I have used fer- 

 rous ammonia sulphate) be dissolved together with 

 a little uranic nitrate, we have a solution which, with 

 a soluble cyanide, gives a purple precipitate, or, in 

 very dilute solutions of the cyanide, a grayish purple. 



T?his test is very delicate. Used in the manner to 

 be presently described, a solution of potassic cyanide, 

 containing 5^0 of a grain of anhydrous hydrocyanic 

 acid, gives a perfectly distinct reaction. It is, there- 

 fore, not exceeded in delicacy by any known test for 

 that substance. 



The solution of iron and uranium must not be acid- 

 ulated, but, on the contrary, should be quite neutral, 

 and so dilute as to be nearly colorless. A grain or 

 two of each salt may* be dissolved in a half-ounce of 

 water. Two or three drops of the mixed solution 

 are to be placed in a clean, white porcelain capsule, 



