CHEMICAL SCIENCE. 241 



the shape of thick crucibles. Their covers are likewise made of lime. 

 M. Berthier observed that hydraulic limes were readily fused at a 

 high temperature, and I have found that very pure lime very frequently 

 agglutinated. It is, therefore, indispensable to employ a somewhat 

 porous lime. With regard to the combustible, it must be very porous 

 and in a state of very fine division ; and I should add. that I succeeded 

 only when I made use of the residue of the imperfect combustion of 

 coal, the clinkers mixed with cinders which fall from the grate of the 

 heating apparatus and still at the Ecole Normale, passed through a . 

 wire seive. With coal of the best quality, in very small particles, the 

 effects are much more feeble, and do not differ from those which have 

 already been obtained. Comptes Rendus, Nov. 1852. 



ARTIFICIAL FORMATION OF THE DIAMOND. 



Considerable interest has recently been excited in the scientific 

 circles of Paris, by the announcement of M. Despretz to the Academy, 

 of the artificial formation of diamond powder. Some time since M. 

 Despretz collected a large number of powerful galvanic batteries, and 

 concentrated all their fires upon poles of carbon enclosed in glass. 

 Carbon, which hitherto had been deemed absolutely fixed, exposed to 

 an extreme temperature, gave out vapors which immediately were 

 precipitated upon the sides of the vase; but here, again, the direct in- 

 tervention of heat furnished only an amorphous powder, a sort of 

 lampblack, without the least crystalline appearance. This experiment 

 was regarded as having furnished new arguments against the suppo- 

 sition that the diamond was of igneous origin. 



Despretz, however, continued his researches, believing in the prac- 

 ticability of effecting his object. After having ascertained that the 

 precipitation of the vapors of carbon disengaged at a high tempera- 

 ture, gave only a black powder like lamp-black, he endeavored- to op- 

 erate without heat, and to compensate the weakness of the action he 

 intended to excite by the intervention of time. To effect this, he 

 made use of an apparatus invented by M. Kuhmkorff, which, placed 

 in connection with a simple voltaic couple, gives a series of discharges 

 caused by the development of the current of induction. As long as 

 this battery retains enough power, the instrument illuminates the 

 interior of a globe from which the air has been exhausted, with an 

 arc of electric light, which is periodically reproduced every few 

 seconds. This arc developes very little heat, and yet in the course 

 'of time it carries from one pole to the other very small quantities of 

 matter. M. Despretz thought that if he placed at the positive pole a 

 mass of pure carbon, and disposed platina wires at the negative pole, 

 that the transfer and the accumulation of the carbon would take place 

 under circumstances favorable to crystallization. He made the ex- 

 periment as follows : Placing at one, the inferior pole of a voltaic 

 battery a cylinder of pure charcoal (its purity being secured by pre- 

 paring it from crystallized white sugar candy,) and at the superior 

 pole a bundle of fine platinum wires so arranged that the charcoal 



