178 Scientific Intelligence. — Geology. 



the certainty of my conclusions. — (Quarterly Journal of the Geolo* 

 gical Society, vol. ix., No. 36.) 



2. Artificial Production of Diamond Powder. — Some consider- 

 able sensation has been produced in the scientific circles of Paris, by 

 the announcement of the artificial formation of diamond powder. M. 

 Despretz has made two communications to the Academie des Sciences 

 upon carbon. In these, he states, that placing at one, the inferior, 

 pole of a voltaic battery, a cylinder of pure charcoal (its purity being 

 secured by preparing it from crystallized white sugar-candy), and at 

 the superior pole a bundle of fine platinum wires, so arranged that, 

 the charcoal was in the red portion of the electric arc, and the plati- 

 num in the violet ; he found the carbon volatilized, and collected on 

 the platinum wires in a changed state. In these experiments, the 

 current has been continued during a month in activity, and the powder 

 collected on the wires has been found to be sufficiently hard to polish 

 rubies with great rapidity, and when burnt, it left no residue. M. 

 Despretz asks himself, Have I obtained crystals of carbon which I 

 can separate and weigh, in which I can determine the index of re- 

 fraction and the angle of polarization, without doubt 1 No. I have 

 simply produced by the electric arc, and by weak voltaic currents, 

 carbon crystallized in black octohedrons, in colourless and trans- 

 lucent octohedrons, in plates also colourless and translucent, which 

 possess the hardness of the powder of the diamond, and which dis- 

 appear in combustion without any sensible residue. A similar 

 result has been obtained by decomposing a mixture of chloride of car- 

 bon and alcohol, by weak galvanic currents. The black powder de- 

 posited, was found to possess equal hardness with that which was 

 sublimed, and rubies were readily polished by it. A few years since, 

 graphite and coke were formed from diamonds. We now appear to 

 be advancing towards the conversion of graphite and coke into dia- 

 monds. — (Athenceum, No 1355.) 



GEOLOGY. 



3. Use of Salt among the Natives in Namaqua Land, South 

 Africa. — The Namaquas occasionally use salt, but they set no store 

 upon it. There is no doubt, that people who live on meat and milk 

 would require salt much less than those who live on vegetables ; but 

 half the Damaras subsist simply on pig-nuts, — the most worthless 

 and indigestible of food, and requiring to be eaten in excessive quan- 

 tities to afford enough nourishment to support life. The Hottentots 

 of Walfisch Bay, who live almost entirely on the nara gourd, and 

 who have the sea on one side, and salt springs in front of them, 

 hardly even take the trouble to collect salt, which they certainly 

 would do if they felt that craving for it which distresses many 

 Europeans. The last fact that I have to mention with reference to 

 salt, is that the game in the Swa Kop, do not frequent the salt rocks 



