20 MR. WATSON SMITH ON ISODINAPHTHYL. 



bably due to the presence of a little naphthalin vapour 

 mechanically carried over, though certainly a trace of 

 acetylene might be present at times, and would then ac- 

 count for it. 



If a calculation be made from the volume of gas evolved, 

 it will be found that this quantity is too great to stand 

 good for the equation 



7 C IO H 8 = 5 C 14 H IO + 6H. 

 Weight of H actually evolved .... =0*2107 grm. 

 „ „ required for the above reaction =o* 1 86 1 „ 



The above is sufficient to show that, as the amount of 

 hydrogen evolved was too great to stand good for the 

 above equation, the body formed from the decomposition 

 (seeing that there was no appreciable separation of carbon) 

 must be richer in carbon and poorer in hydrogen than 

 anthracene is. This point will be again referred to. 



Now the crude substance which had been accumulated 

 amounted to 26*3 grms. — that is, 17*23 per cent, on the 

 naphthalin used. These 26*3 grams of crude substance 

 were placed in a small retort with thermometer, and sub- 

 mitted to fractional distillation. A very small quantity of 

 naphthalin came over first, below 220 C. ; and then the 

 temperature very rapidly rose to considerably above 360 

 C, when most of the body distilled over, leaving a minute 

 quantity of pitch in the retort. In distilling, almost 

 all the substance solidified in the neck of the retort, which 

 had to be kept very hot towards the end of the operation, 

 to get the substance to run down fused into the receiver. 

 At this stage the distilled product closely resembled anthra- 

 cene in a similar stage of purification, but did not possess 

 the peculiar odour which characterizes that body in the 

 crude state, being almost entirely free from odour. 



To purify further, the solid hard substance was crushed 

 in a mortar and made into a thin homogeneous paste with 



