MR. WATSON SMITH ON ISODINAPHTHYL. 21 



light shale-spirit (or petroleum-spirit) , in both of which it 

 is much less soluble than in benzol. It was then drained 

 on a filter,, washed again several times with petroleum- or 

 shale-spirit, drained, pressed in blotting-paper, and dried 

 at a temperature fully sufficient to volatilize the spirit. 

 By this washing it was freed from a small quantity of resin- 

 ous matter, and from a citron-yellow-coloured substance, 

 which coloured the spirit mother-liquors yellow by direct 

 transmitted light, exhibiting a fine blue fluorescence by re- 

 flected light. 



This fluorescence is similarly acquired when any fluids 

 possessing any solvent action are substituted for the shale- 

 spirit. 



Finally the dried substance was sublimed at as low a 

 temperature as possible. The sublimate consisted of a 

 faintly yellowish white inodorous powder, precisely re- 

 sembling commercial anthracene sublimed under like con- 

 ditions, but not possessing the slightest odour. The sub- 

 limate may also be obtained in delicate little plates, by 

 very careful and slow sublimation. When possessing the 

 faintest yellow tint, this powder imparts a delicate blue 

 fluorescence to any solvent used. 



In another preparation of a further quantity of crude 

 substance, a large iron tube, about 4 or 5 feet long, and 

 about 3^ inches diameter was used, being placed in a char- 

 coal fire. The heat was almost to whiteness. In this 

 case there was a connexion with a pneumatic trough, 

 the open end of the tube dipping into an iron pan, acting 

 as receiver. Immense volumes of black smoke were libe- 

 rated at first * ; however, on moderating the heat some- 

 what, whilst the dense black smoke still poured out, a 

 quantity of undecomposed naphthalin and other matters 

 came over, dropping into the receiver. The black, almost 



* Probably caused by the admittance of a small amount of air acci- 

 dentally. 



