98 Chronicles of Science. [Jan.., 



has exposed an ordinary bromo-iodized plate, and then thrown it 

 into a dilute solution of pemitrate of mercury, by which the iodide 

 and bromide of silver are dissolved, and the film left clear as glass. 

 Nevertheless, after the plate had been well washed, the image 

 appeared when the developer was applied. 



Two correspondents of the ' Chemical News,' Mr. Spiller and 

 Mr. Clarke, have recently called attention to the liability of the 

 composition for making red fire to spontaneous ignition. The fact 

 was well known with regard to red fire, but Mr. Clarke informs us 

 that the composition for purple fire made with black oxide of copper, 

 as it usually is, is almost certain to take fire of itself sooner or 

 later ; and he adds, that carbonate of copper should always be used 

 in preference to the oxide. 



On the border-land, between mineral and purely organic 

 chemistry, we may notice the formation by E. Maly of an ether of 

 tungstic acid by treating oxychloride of tungsten with strong 

 alcohol. Tungstic ether forms a hard, brittle, glassy mass, insoluble 

 in water, alcohol, and ether. When heated on platinum foil it burns 

 with a smoky flame, and in the end yellow tungstic acid is left as 

 the residue. 



We have several times mentioned M. Berthelot's researches on 

 the hydrocarbons, which have already thrown so much light on the 

 constitution of these bodies, and which the author continues to 

 pursue with unwearied industry. One of his latest published 

 results is the synthesis of benzol. Our readers will remember that 

 M. Berthelot has effected the direct synthesis of acetylene C, H 2 by 

 the union of carbon and hydrogen. He has now passed the 

 acetylene so produced through a red-hot tube, by which he obtained 

 a yellowish liquid, more than one half of which was benzol, the 

 remainder being polymers, styrol, fluorescent carbides of hydrogen 

 and retene, &c. The author therefore regards benzol as tri- 

 acetylene : — 



C12 H 6 = 3 C 4 Hg. 

 The reader who wishes to peruse this important paper at length 

 will find it in the places indicated below.* 



In another paper M. Berthelot describes the results of the action 

 of heat on benzol and analogous hydrocarbons. Benzol when 

 passed through a red-hot tube is decomposed with condensation into 

 several hydrocarbons, the principal being phenyl C^ H ln . Chrysen 

 C 36 H lg is another product, and there is a residue of other solid 

 hydrocarbons. A mixture of benzol and ethylene passed through a 

 red-hot tube yielded styrol C 16 H 8 and naphthahn C 2J H 8 as the 

 principal products. Styrol heated to redness breaks up into benzol 

 and acetylene, and reciprocally a mixture of benzol and acetylene 



* ' Comptes Rerulus.' xiii. p. 472. ' Chemical News,' No. 365. p. 224. 



