1896.] MICROSCOPICAL JOUKJNAL. 141 



Mr. Attwood had mounted for examination under tlie 

 microscope a small fragment of what is called "carbon- 

 ate," or diamond carbon. Bahia, Brazil, produced at 

 one time large quantities of the carbonate. 

 Its hardness is identical with the white diamond, and in 

 structure it is porous, so much that is resembles pom- 

 ice stone. The fragment he had mounted was taken from 

 the Yellow Jacket diamond drill, at Virginia City, Nev- 

 ada. The drill penetrated the rock below the gold and 

 silver ores of the Gomstock lode at a depth of over 4,000 

 feet, when they met with hot water. 



Should the minerals forming the rock be too small 

 to be seen with the common lens, a microscopic 

 section will have to be cut. The process is a simple one,- 

 but requires patient and skillful treatment to produce a 

 section thin enough for a full view of its structure. Mr. 

 AHwood had two section thus prepared from the hang- 

 ing wall of the Keystone mine, Amador county, at the 

 thousand-foot level, one to sIioav color and texture, the 

 other to be examined by polarized light. 



Altogether the demonstration was a good one, and the 

 paper was attentively listened to. 



EDITORIAL. 



Transactions of the American Microscopical Society for 

 1895. — This volume, consisting of 376 pp. and numerous plates, 

 reached us on February 15, 1896. It relates to the meeting of 

 Augast 31 to 23, 1895. It has therefore taken about seven 

 months to publish it. This is probably as prompt as it has 

 ever been done, and reflects credit upon the Secretary, Dr. 

 Wm. C. Krauss, who has had the matter in charge. Under 

 the recent scheme of quarterly installments, the first part usually 

 required six or seven months, the second part several more and 

 the third or fourth parts ran down upon the following meeting. 

 It will be seen that Dr. Krauss has issued the entire publica- 



