246 Mr. H. G. Madan on some Organic 



many purposes, I thought it worth while to prepare some of 

 the ketone and examine its properties. I now exhibit a speci- 

 men of it. 



I prepared it by the general method devised by Grucarevic 

 and Merz (Berichte der deutschen chemischen Gesellschaft, vi. 

 pp. 60 & 1238) for obtaining double ketones ; viz. by heating- 

 together benzoyl chloride and naphthalene, and placing in 

 the mixture a strip of zinc. The product was fractionally 

 distilled, to free it from the excess of naphthalene, and was 

 finally obtained as a thick yellow oil, boiling at a point so 

 nearly that of mercury that a mercury-thermometer could 

 not be used to determine it. In properties it seems a very 

 stable, neutral, harmless substance like Canada balsam; but 

 unfortunately it does not appear capable of hardening like 

 balsam, and hence it is not by itself adapted for a cement. It 

 is insoluble in water, but dissolves readily in alcohol and 

 benzol. 



Its refractive index was determined in the usual way, a 

 hollow prism (of refracting angle of 59° 48') being filled 

 with it, and the angle of minimum deviation for yellow sodium- 

 light observed with a refractometer ; from which data the 

 usual formula gave as its refractive index, 1*666. This is 

 even higher than that of carbon disulphide (1*63), and very 

 nearly the same as that of calcspar given above. 



I compared its dispersive power with that of a prism of 

 very dense glass (refractive index 1*73) having a refracting 

 angle of 60°, with the following results :- 



Fraunhofer's 



Ketone. 



Glass. 



Carbon disul- 

 phide. 



line. 



B . . 

 E . . 



. 1-654 

 . 1-678 



1-725 

 1-744 



1-617 

 1-643 



From this it is easily seen that the coefficient of dispersion of 

 the ketone is 1 J times that of the glass, and almost exactly the 

 same as that of carbon disulphide. 



I have made the compound of the ketone with bromine, 

 referred to by M. Bertrand, but I hesitate to recommend it 

 as a cement, at any rate for anything made of calcspar; as 

 it seems liable (like many similar bromides) to decompose 

 with formation of hydrobromic acid, which of course acts 

 upon the spar. 



The ketone itself has a refractive index quite sufficiently 

 high, if only some means can be found of hardening it. 



I cannot, however, yet vouch for its permanency. It was 

 made in August last, and remained for several months without 

 change; but it has lately shown a tendency to pass from the 



