274 ANNUAL OF SCIENTIFIC DISCOVERY. 



mens, but still they lead to the conclusion, that the density is very 

 nearly the same as that of the diamond. The specimens were not 

 altered by a long calcination at a bright red heat, so that they cannot 

 contain any substance volatilizable by calcination. This result ren- 

 ders improbable the idea of Liebig, that diamonds are derived from 

 the transformation of organic vegetable matter. The three specimens 

 were successively burned in pure oxygen gas in the apparatus used 

 for the combustion of the diamond, and 100 of the first specimens 

 gave carbon 96.84, ash 2.03, loss 1.13; in the others the carbon was 

 99.73 and 99.87, the ash 0.24 and 0.27, and the loss but 0.03 and 

 0.86. The analysis, therefore, shows that they are composed wholly 

 of carbon and ash. The analysis of the first specimen, however, is 

 believed to be erroneous. The ash was of a yellowish color, and 

 under the microscope appeared to be composed of ferruginous alumina 

 and small transparent crystals. Jameson's Journal. 



PLUMBIC OCHRE FROM MEXICO. 



WE have received from Prof. Baily, of West Point, specimens of 

 plumbic ochre, or native litharge, from New Mexico. He writes 

 concerning it : " It was given to me by Major Geo. Thomas, of 

 U. S. Army, who got it in New Mexico, where he said it was called 

 ' silver flux,' and used in working silver ores. Thinking it might be 

 only an artificial ' litharge,' I wrote to Major Henry for particulars, 

 and he says, 'I am certain that it is obtained in many places in the 

 province of Chihuahua and Cohahuila. Whilst stationed at Saltillo, 

 I saw some forty or fifty sacks of it which had been taken from a 

 mine near Mazapel, a mining town, some one hundred miles south of 

 Saltillo. I saw a few pieces which had been picked up by officers in 

 the streams between Ceralvo and Monterey, and also in the Sabinas 

 River in the province of Cohahuila. This leads me to suppose this 

 ore occurs in the range of mountains running nearly north and south 

 through Cohahuila, and terminating about twentytfive miles north of 

 the city of Monterey.' We have examined the specimens sent us 

 by Prof. Bailey, and find them to be yellow oxide of lead. The color 

 is between orpiment and sulphur-yellow, and it glistens like a granu- 

 lar mica of a nearly golden color. The natural surface is slightly 

 crystalline and shining, and when broken it has a scaly texture. 

 Silliman's Journal. 



DURABILITY OF STONE. 



THE Secretary of the Interior, in his report to Congress, says, 

 " In applying the appropriation for the painting and repairs of the 

 Capitol, it became necessary to examine with care the condition of 

 the walls, and to remove such portions of the stone as were crumbling 

 or falling off in scales, that the coat of paint might be laid upon a 

 sound and solid surface. In this examination it was found that many 

 of the stones, especially those near the base of the building, were 



