214 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



above named, for the specific heats of the three elements are 

 as follows: carbon, 0.46; boron, 0.5; and silicon, 0.205. These 

 numbers, multiplied by the atomic weights, give values in 

 accordance with Dulong and Petit's law, so that carbon, bo- 

 ron, and silicon can hereafter be regarded as exceptions only 

 at low temperatures. Dr. Weber's extremely valuable paper 

 concludes with some speculations, based upon his results, as 

 to the nature of carbon, which he thinks may after all prove 

 to be not an element, but a compound. 7 A, 3Iarch and 

 April, 1875, 161, 276. 



A IIYDKATE OF CARBON. 



Whether or no any true hydrate of carbon can exist has 

 long been an open question. It is now settled affirmatively 

 by Schutzenberger and Bourgeois. These savants treated 

 white cast iron in coarse powder with a solution of copper 

 sulphate, and subsequently with ferric chloride and hydro- 

 chloric acid. The metal was thus entirely removed, and a 

 pulverulent, blackish-brown body in small quantity remain- 

 ed. This body was found to be a hydrate of carbon contain- 

 ing eleven atoms of carbon united with three molecules of 

 water. Nitric acid attacked it energetically, chan^imr it 

 into a reddish-brown amorphous substance, which proved to 

 be a new acid of somewhat complicated structure. To this 

 acid the discoverers have given the name nitrographitoic. 

 It also seems to be formed by the direct action of nitric acid 

 upon cast iron. Bulletin de la Soc. Chimique, May 5, 387. 



CRYOHYDRATES. 



Frederick Guthrie, in a paper upon "Salt Solutions and 

 Attached Water," has described a curious new series of com- 

 pounds, which he terms " cryohydrates." He finds that w r hen 

 any saline solution is exposed to a freezing mixture, a crop 

 of crystals after a while separates out, containing the salt 

 plus a definite quantity of water. Thus a saturated brine 

 affords crystals containing one molecule of common salt 

 united with ten molecules of water. Sulphate of zinc, un- 

 der similar circumstances, forms a cryohydrate with twenty 

 molecules of water; magnesium sulphate with twenty-four 

 molecules, saltpetre with forty- four, sodium sulphate with 

 one hundred and sixty-six, and so on. Similar cryohydrates 



