OF ARTS AND SCIENCES. 317 



Beilstein, and afterward Neuhof, obtained their so-called mercaptan 

 (melting-point 84°-85°) by boiling the substances together for a long 

 time, which we find, as already stated, gives the disulphide as prin- 

 cipal product ; furthermore, their crystals were formed only after long 

 exposure of the liquid product of the reaction to the air. It would 

 seem, therefore, that their substance must have been the disulphide, 

 the percentage composition of which is essentially the same as that 

 of the mercaptan, and therefore the two substances could not be dis- 

 tinguished by analysis, but only by treatment with mercuric oxide, 

 which they do not seem to have tried. On the other hand, the melt- 

 ing-point of their substance (84°) is much higher than that of ours 

 (59°), and it is certainly strange that a mixture of an ortho- and para- 

 compound should melt at a higher temperature than the pure para- 

 compound ; they also describe it as crystallizing in vitreous octahedra, 

 while our substance crystallizes even by slow evaporation of a benzole 

 solution in the flattened needles already mentioned. 



Parachlorbenzyldisulphidedioxide, (C 6 H 4 C1CH 2 ) 2 S.,0 2 , was made by 

 adding the necessaiy amount of chromic anhydride dissolved in glacial 

 acetic acid to a weighed quantity of the disulphide also dissolved in 

 glacial acetic acid ; on the addition of water, an oil was deposited, 

 which became solid on standing in the cold, and was purified by crys- 

 tallization from alcohol. 



0.5870 gr. of the substance dried in vacuo gave, by combustion, 

 1.0390 grs. C0 2 and 0.1838 gr. of H 2 0. 



It is a waxy solid, which becomes crystalline after some time ; the 

 melting-point of the specimen analyzed was 120°; it is insoluble in 

 water, readily soluble in alcohol, ether, benzole, carbonic disulphide, 

 and glacial acetic acid. 



The Parachlorbenzylethylether was made by boiling parachlorben- 

 zylbromide with an alcoholic solution of sodic hydrate ; the product 

 was precipitated with water, and the oil purified by distillation with 

 steam. It was a colorless liquid, which distilled over between 

 215°-225°, and did not solidify when cooled to — 12°. As its prop- 

 erties therefore agreed essentially with those ascribed to it by 



