300 British Association for the Advancement of Science. 
Dr. B. also Gunibdhiented a paper “ On the possibility of obtain- 
ing by Voltaic action, crystalline metals, intermediate between 
the Poles or Electrodes,” and exhibited a mass of plaster of Paris 
(upon which he had operated ) containing little veins of copper 
disseminated through it in ‘every direction, which presented a 
marked ee to those met aatthe on the large — in na- 
ture. 
~ Prof. Johinistot desdribad a Ninspouied of siudphaite of lime; de- 
posited from a high-pressure. boiler, containing half an atom of 
water, and in this Y scteteu ee from any Other As 
of the kind. 
‘Mr. Phillips stated that the B Iue Pigment.submitted last year 
by Dr. Trail, was ‘Prussian blue hues es diluted, ei rendered 
pale by ferrocyanide of antimony. 
Prof: Graham read a Note on the Constitution of Salts. He 
wished to draw attention toa distinction in saline combinations 
which is*too often overlooked, and confusion thereby occasioned. 
The orders of monobasic, bibasic, and tribasic salts, of which the 
phosphates proved types, have lately been greatly enlarged by the 
discoveries of Liebig and Dumas respecting vegetable acids, and 
the distinctive characters of thése-orders are well understood. 
The best proof that an acid is bibasic or tribasic is its combining 
at once with two bases which are isomorphous, or belong to the 
same natural family,—as: ‘phosphoric acid does with soda and 
ammonia in microcosmic salt, and tartaric acid with potassa and 
soda in Rochelle.salt. Water and magnesia; water and barytes, 
water and oxide of lead, are also constantly associated as bases 
in bibasic and tribasic salts, but never in true double salts, or com- 
binations of two or more salts with each other, with which salts 
of the preceding orders are often confounded. But it is too gen- 
erally supposed that a metallic oxide cannot exist in a saline com- 
bination, except in the capacity of base, although in most of those ~ 
bodies whiek are at present termed swb-salts, the whole or a por- 
tion of the metallic oxide is*certainly not basic, but is attached to 
a really neutral salt; in a capacity similar to that of constitutional 
water, or water of crystallization. 'The test of the  non-basic 
character of water or a metallic oxide in a compound, is the ab- 
sence of a mong irene mes containing an oxide of the ates 
class. 
