24 MR. WATSON SMITH ON ISODINAPHTHYL. 



parts of potassium bichromate and sulphuric acid, when 

 oxidation took place, as energetically as in the case of an- 

 thracene under like treatment. No crystals bearing any 

 resemblance to those of anthrachinon could be obtained on 

 treating with benzol. From the product which was ob- 

 tained, no substance similar to alizarin, nor in fact any 

 colouring-matter, could be obtained. 



Cold sulphuric acid is without action upon this body ; 

 but when heated the acid slowly dissolves it, when, if it be 

 quite pure, a very faint purplish-tinted solution is formed; 

 if not quite pure, but containing a trace of the yellow- 

 coloured body mentioned before, a violet or purple solution 

 is formed, becoming green and then reddish-brown on 

 further warming. (Vide page 22.) 



Hot nitric acid oxidizes it, with liberation of nitrous 

 fumes, forming heavy oily drops of a nitro-compound of a 

 red colour ; on farther boiling, with a larger excess of acid, 

 this compound is slowly dissolved. On addition of water, 

 a light yellow floccular precipitate is thrown down abun- 

 dantly. 



Placed in a glass tube and chlorine passed over it in the 

 cold, no action takes place; and even on warming to a 

 considerable extent, no change appears to occur. Treated 

 with bromine in the cold, combination takes place with 

 very energetic action. 



After many repeated experiments on the subject, I have 

 come to the conclusion that it is impossible to distil pure 

 naphthalin to dryness in any quantity without this body 

 being formed in minute quantity. This may be observed 

 by dipping the thermometer down nearly to the bottom of 

 the retort, when the last minute quantity is being vapour- 

 ized; the thermometer lowered into this vapour, will be 

 observed speedily to indicate a high temperature, the 

 mercury rapidly rising towards 350 C. If this does 

 not take place on the first distillation, — if the naphthalin, 



