94 



CHEMISTRY. 



gun-cotton yielded an inflammable film on evapora- 

 tion to drvness. Pinewood instantly blackened. 



From tne various physical and chemical properties 

 of the anhydrous acid, the author concludes that it lies 

 between hydrochloric acid and water, but is much 

 more closely allied to the former than to the latter. 

 It is more readily liquefied than hydrochloric acid, 

 but less readily than steam : like hydrochloric acid, it 

 decora poses all carbonates ; like water, it unites power- 

 fully with sulphuric and phosphoric anhydrides with 

 great evolution of heat. The fluorides of the alkali- 

 metals unite violently with hydrofluoric acid, as the 

 oxides of those metals unite with water : the hydrated 

 fluorides of the alkali-metals also, like the hydrated 

 fixed alkalies, have a strongly-alkaline reaction, 

 and are capable of expelling ammonia from its salts. 

 It may be further remarked that the atomic num- 

 ber of fluorine lies between that of oxygen and 

 chlorine : and the atomic number of oxygen, added 

 to that of fluorine, nearly equals that of chlorine. 



Analysis of Varieties of Carbon. Berthelot 

 is the author of an elaborate paper, communi- 

 cated to the French Academy of Sciences, on 

 the varieties of carbon, showing that the num- 

 ber of modifications of that element is greater 

 than had been supposed. His researches were 

 based upon Brodie's method of oxidizing gra- 

 phites by means of nitric acid and chlorate of 

 potash. From an abstract of the paper, in the 

 American Journal of Science for May, we 

 quote: 



By these reagents diamond is not sensibly oxi- 

 dized ; the different varieties of amorphous carbon 

 are changed into humus-like substances of a yellowish- 

 brown color, soluble in water and varying according 

 to the variety of carbon analyzed, while the graphites 

 are converted into graphitic oxides which differ with 

 the nature of the graphites which furnish them. 

 Berthelot gives the name pyrographitic oxides to the 

 black powder which remains when the graphitic 

 oxides are heated. They also contain oxygen and 

 hydrogen as well as carbon. Native plumbago, or, as 

 Berthelot terms it, plumbagine, already examined by 

 Brodie, yields a graphitic oxide in pale-yellow mica- 

 ceous scales, insoluble in all reagents, and not decom- 

 posed with deflagration and intumescence by heat. 

 Treated with chlorate of potash and nitric acid it 

 yields graphitic oxide with all its original properties. 

 Graphitic oxide from electric graphite carbon 

 points from a large battery is a maroon-colored pow- 

 der which does not agglomerate during desiccation. 

 This character is also constant. The hydrographitic 

 oxide does not intumesce when heated, and when 

 oxidized reproduces the original oxide. This form of 

 graphitic oxide is also decomposed by heat with de- 

 flagration, but yields a heavy powder which is not 

 flaky. By oxidation the pyrographitic oxide disap- 

 pears almost wholly, leaving some grains of graphitic 

 oxide with its original properties. 



All the pyrographitic oxides, when treated with 

 lodhydric acid in solution at 280 C., yield hydrogen 

 containing about 6 per cent, of marsh-gas, leaving, 

 however, a considerable quantity of a black carbona- 



WOft residue. The author compares the graphites 

 amorphous carbons, and their derivatives, with the 

 hydrates of carbon and ulmic matters, and believes 

 that the varieties of amorphous carbon represent 



miymeric states of the true carbon which is not yet 



, TH- m the fre . or uncondensed form. In studying 

 the different varieties of carbon, Berthelot has arrived 



t the following results, in addition to those related 



>ove : Coke recently calcined is entirely dissolved 



p \V- ng a ? oluble compound of an intense color. Me- 



lic carbon, deposited from hydrocarbon vapors 



ted in a porcelain tube, is dissolved with very 



Teat difficulty but completely. The same is true for 

 gas-retort carbon, and some substances called arti- 



ficial graphites. Anthracite, animal charcoal, and the 

 carbonaceous matter from the Orgueil meteorite, 

 were also completely oxidized, but lampblack left a 

 trace of graphitic oxide. The intense heat produced 

 by combustion in oxygen converts a small portion of 

 gas-retort carbon into graphite. Berthelot suggests 

 that it is in this manner that natural graphite has 

 been formed, the amorphous carbon, being more oxi- 

 dizable at a low temperature, having been gradually 

 dissolved. This view derives some support from the 

 presence of a trace of graphite in lampblack. Elec- 

 tricity also converts amorphous carbon into graphite, 

 the carbon carried over to the negative pole being 

 found to contain a considerable quantity of the latter, 

 while the positive pole contained only a trace. The 

 actual transference of the carbon is not, however, 

 necessary for the formation of graphite ; carbon from 

 sugar softened by the heat from a battery of 600 

 pairs being found to contain graphite in large pro- 

 portion. Carbon separated from hydrocarbons by 

 the agency of heat does not contain a trace of graphite, 

 while that which is separated by heat from the sul- 

 phide or chloride of carbon, or by chlorine from bo- 

 ron, contains a considerable quantity. 



The Ignition Point of Vapors. Mr. TV. R. 

 Hutton, of Glasgow, has determined the de- 

 gree of heat at which the vapors of a number 

 of liquids catch fire from a burning candle at a 

 distance of 1.5 inches, or 0.5 inches from the 

 surface of the fluid. Annexed is a tabular 

 statement of the results of his experiments. 



Nitrification. Mr. S. W. Johnson furnishes 

 to the American Journal of Science for March 

 a paper on the formation of nitrogen com- 

 pounds artificially and in a state of nature. 

 With respect to the natural process of such 

 formation, he is led to the conclusion that free 

 nitrogen enters into combination in all cases 



