16 MR. WATSON SMITH ON ISODINAPHTHYL. 



tain hydrocarbons upon one another, when conducted 

 through a red hot tube. In one of these experiments he 

 passes the vapour of naphthalin with hydrogen through 

 the tube ; and as to the result he says, " Almost no action 

 at all takes place, the naphthalin remaining almost quite 

 unaltered, and only a little benzol and acetylene are ob- 

 tained." 



C«H 4 [C,H,(C,H0] +H, = C 6 H 4 + 2C,H,. 



Naphthalin. Benzol. Acetylene. 



About nine months ago I undertook, at the suggestion 

 of Mr. John Barrow, in the laboratory of whose works I 

 was then engaged, the investigation of the action of heat 

 upon naphthalin, with the object of discovering whether by 

 this means it is possible to obtain anthracene, according 



the equation 



7(C,oH 8 ) = 5 C, 4 H IO + 6H. 



This reaction Mr. Barrow supposed might take place on 

 passing the naphthalin vapours through a red-hot tube. 

 I accordingly tried a number of preliminary experiments 

 in this direction, of which the results were as follows : — 



ist. The odour and colour of the naphthalin which 

 came through the tube were perceptibly altered ; the colour 

 became a deeper brown in proportion as the temperature 

 of the tube was higher. At an incipient white heat a 

 considerable quantity of black smoke came over with the 

 distillate. 



2ndly. A gaseous product was obtained proportionately 

 larger in amount as the temperatnre employed was 

 higher. 



3rdly. On distilling the brown mass of naphthalin 

 coming through the tube, there was invariably left in 

 the retort a minute quantity whose boiling-point was 

 above 350 Cent. 



I now prepared some pure naphthalin, by treating a 

 quantity of the crude stuff, whilst fused, with warm concen- 



