PROCEEDINQS OF THE POLYTECHNIC ASSOCIATION. 331 



Mr. Enos Stevens desired to correct an impression made ref^arding- the 

 value of g'un-cotton in blnsting. Its action is violent, and it crumbles the 

 stone in its immediate vicinity. Where it is desirable to separate rock in 

 regular sixes, it is better to use gunpowder in the series of holes drilled in 

 the same right line. 



Diamonds. 



Dr. Percy, in a lecture reported at length in the London Chemical News, 

 describes the various localities where diauionds have been found, and the 

 chief rocks constituting such districts. The quartzite is a silicious rock to 

 which the name of itacolumnite has been given, from Itacolumni, the name 

 of a town. It is found in some cases to be flexible ; this is owing to the 

 interposition of little micaceous scales. Geologists s^ate that it is, beyond 

 doubt, a metamorphic rock; that is, a rock which has been changed mate- 

 rially subsequent to jts deposition. No fossils have been found in it. The 

 itacolumnite alternates with metamorphic schist. The latter is very easily 

 disintegrated or softened to a great deptli. It is said the softening is due 

 to heavy rains, reported to contain nitric acid after storms. In tiie pro- 

 ducts of disintegration of these rocks, numerous rare minerals, besides the 

 diamond, were found. 



In the Ural district, diamonds have been found since Humboldt's visit in 

 1829. He suggested the probable existence of diamonds there from the 

 geological similarity of the district to that of Brazil. A few diamonds have 

 been found in the itacolumnite, occurring in North Carolina and Georgia. 



Now comes the question, and it is a question which has not yet received 

 solution — if this itacolumnite be, as there is no doubt it is, a rock of sedi- 

 mentary origin, have the diamonds been developed in this rock subsequent 

 to its deposition; or derived from the preexisting rock, out of which this 

 sedimentary rock has been made? 



"With regard to the possibility of making diamonds, scarcely a chemist 

 is to be found who doubts that, one day or other, diamonds will be made. 

 Various attempts have been made with the bisulphide of carbon. We 

 were informed, a good many years ago, that some French chemist had suc- 

 ceeded in making diamonds by plunging phosphorus into this liquid, com- 

 posed of sulphur and carbon, which has a high refractive power. It was 

 said that in this way the diamond might be produced, the sulphur being 

 taken away from the compound by the phosphorus and the carbon being 

 set free in a crystalline form. Then again it has been attempted to decom- 

 pose the sulphide of carbon by means of silver. He, the lecturer, had kept 

 a piece of silver in that liquid for ten or twelve years. The silver became 

 blackened on the surface, which seemed to be an indication of decomposi- 

 tion, as though the sulphur were taken away so as to allow the gradual 

 elimination of the carbon. Unfortunately, it happened that this bisulphide 

 of carbon operated upon had not been entirely free from sulphur, and all 

 that the silver did was to take out the sulphur which had been contained 

 in a state of solution in the sulphide. At presenr, truth compelled him to 

 say that we have no clue whatever, so far as he knew, as to the mode in 

 which diamonds have been produced by nature. Most certain it is that a 

 high temperature has not been employed, because it loses its character at a 



