204 Annals of the Philosophical Club 



identical with real stones and appeared to be crystalline^ 

 The question of making them for sale had been considered, 

 but they proved to be insufficiently perfect. By means of 

 a battery M. Deprez had produced diamond crystals from 

 a solution the composition of which was kept secret. They 

 were stated to be identical with the real stones, but had a 

 smoky tint. Some of them had been exhibited at the 

 French Academy. 



Dr. Debus spoke of an analysis which he had made of the 

 colouring matter of some green muslin. In a square yard 

 of one specimen he had found 60 grains of arsenide of 

 copper (Scheele's green), and of another, 10 grains. The 

 colour adhered so slightly to the muslin that, on washing 

 it, all the green was removed. He cut a square yard of the 

 first-named sample into fifty pieces, and gave one for analysis 

 to each of that number of students, and in 20 minutes 

 the room was so full of the fumes of arsenic that doors and 

 windows had to be opened. A ball costume contains 

 from 18 to 20 yards of muslin. An olive-green dye, recently 

 introduced, which is a mixture of arsenious acid and chromate 

 of potash, appears to adhere to the material more firmly 

 than Scheele's green. 



Oct. 25th, 273rd meeting. The subject of poisoning by 

 arsenical dyes was resumed, and Professor Huxley men- 

 tioned a case of severe illness which was traced to the arsenic 

 in the paper of a room. Dr. Carpenter said that he had 

 been unable to obtain evidence of a glazed paper producing 

 an injurious effect. Mr. Abel observed that he had found 

 green glazed paper to contain more arsenic than green 

 flock paper. Professor Frankland suggested that the flock 

 itself might not contain much arsenic, but this might be 

 in the underlying substance which reinforced its colour, and 

 from which it might be more easily detached than from 

 glazed paper. 



Mr. Huggins referred to his remarks on artificial rubies, 

 and said that M. Kreil had succeeded in crystallizing the 

 fused alumina and thus in making true rubies, one of which 

 he exhibited. The mass was kept in a state of fusion for 



