372 Scientific Intelligence. — Chemistry. 



3. The Diamond. — It is evident to geologists, that the diamond has 

 not been formed in the places where it is found. It is obtained from 

 alluvial situations, consisting of rolled stones cemented by a ferrugin- 

 ous or sandy clay, mixed with oxide of iron, quartz, petrified wood, 

 he. 



The mines of Brazil furnish annually from twenty five to thirty 

 thousand carats, that is, from ten to thirteen pounds of rough dia- 

 mond, of which eight or nine hundred carats only can be cut. 



The expense of exploring the diamond mines is estimated at 38 

 francs, 20 cent, per carat. A slave who finds a diamond of more 

 than seventy grains obtains his freedom. 



Diamonds not susceptible of being cut, are sold at from thirty to 

 thirty six francs the carat. 



The term carat, formerly employed to designate the quantity of 

 gold, originated in the country of Shangallas, in Africa, where the na- 

 tives in weighing gold used as weights the grain of a plant, called 

 Jcuara. These grains, transported to India, were employed in weigh- 

 ing diamonds. The weight of the carat is exactly two hundred and 

 five milligrammes, or nearly four grains. 



A rough diamond which can be cut and which weighs less than a 

 carat, sells for forty eight francs per carat. When they surpass a ca- 

 rat in weight, the price is obtained by squaring the weight and multi- 

 plying by forty eight francs. 



The cutting of diamonds is the invention of Louis Berquin of Bru- 

 ges, in 1476. It is effected by means of diamond powder on a hor- 

 izontal wheel of soft steel. All the diamonds found in ancient ar- 

 mor are natural crystals. 



Diamonds are cut either in rose or in brilliant. The brilliant pro- 

 duces the most varied effect of color and light, — the 7'ose corruscates 

 more vividly, but its play is less fine. At present the brilliant ob- 

 tains the preference. 



The price of cut diamonds varies much with their form, purity and 

 color, as well as weight. From j\ to a carat, the mean price is from 

 sixty to two hundred and fifty francs per carat. Above a carat, the 

 square of the weight is multiplied by one hundred and ninety two, — 

 or by a price per carat according to the defects or beauty of the dia- 

 mond. We perceive in the diamond, more remarkably than in any 

 other substance, the wonderful effects of crystallization in altering the 

 consistency and appearances of matter. Calcareous spar and rock 

 crystal also afford remarkable examples. 



