176 



REPORT — 1902. 



25'5 to 32 per cent, of tin. 



The same complex, but containing the Cu^Sn in the larger crystals, 

 and the Alpha only in the minute eutectic. At .32 per cent, the alloy is 

 pure CujSn. 



32 to 38 5 per cent, of tin. 



A complex of Cu^Sn and CujSn, or of two solid solutions of these 

 substances. At 38 5 per cent, the alloy is pure CusSn. 



38'5 to 93 per cent, of tin. 



Large crystalline jalates of Cu.jSn coated with a body that is almost 

 pure CuSn, the whole being immersed in a eutectic of this body and tin. 



93 to 99 per cent, of tin. 



Large crystals of CuSn in a eutectic of this body and tin. 



99 to 100 per cent, of tin. 



Large crystals of tin iu the same eutectic. 



Isomeric Naphthalene Derivatives. — Report of the Committee, consisting 

 o/ Professor W. A. Tilden (Chairman), and Bv.}!. E. Armstrong 

 {Secretary). (Drawn up by the Secretary.) 



Since the last report was written, the behaviour has been studied of the 

 two tri-bromo-;d-naphthols. Nos. 1 and 2, at the ordinary temperature, 

 towards an excess of bromine in presence of aluminium bromide. Each 

 has given two penta-brorao-/3-naphthols, the structure of which at once 

 follows from the nature of the quinones derived from them, and the 

 behaviour of the latter on oxidation. The results obtained can only be 

 explained by assuming that the tri-bromo-/3-naphtliol, No. 2, which was 

 provisionally represented as 



OH 



is in reality 



OH 



It follows, therefore, that the new di-bromophthalic acid (m.p, 195-196°, 

 anhydride, 147° "5) derived from this tri-bromO-/3-naphthol by oxida- 

 tion, is a 3 : 4 di-hromophthalic acid. 



The following scheme illustrates the results obtained ; 



