1851.] OF THE ROYAL INSTITUTION. 49 
common to all these and perhaps to tartaric acid, and only modified a 
little by the super-position as it were of other substances, in combina- 
tion with it, upon the extremities of its molecule. 
He also dwelt on the possibility of the Paratartaric acid being a 
quadribasic as the tartaric acid isa bibasic acid; it being on this 
view a conjugate acid consisting of the two united tartaric acids. 
He then invited attention to the interesting nature of M. Biot’s inves- 
tigation of the action of tartaric acid in solution in water, and he 
showed that here the acid must be supposed capable of combining 
with an indefinite or indeed an infinite amount of water, while in 
other cases again, bodies (such as sugar for instance) exercise no 
effect upon the water and do not seem to combine with, but only to 
be dissolved in it. The former is an instance of a continuous and not 
intermittent sort of combination ; and though we need not anticipate 
a recurrence of the controversy of Berthollet and Proust, yet this 
shows us that the actions of quantity or mass so dwelt on by the 
former are not without a great significance; and that the power that 
can thus enable us to determine such important points in chemical 
statics, is well worthy of the attention of the philosophic mind. 
Dr. Bence Jones permitted a Saccharimeter apparatus of Soleil’s, 
on the double-quartz-plate principle, to be exhibited, and explained 
its use. Mr. Tennant also exhibited a mass of quite transparent 
Iceland spar, and a beautiful crystal of plagiedral quartz. 
Since the delivery of the lecture, a letter has been received from 
M. Pasteur stating that he had forwarded for exhibition at and 
illustration of this lecture, all the finest specimens of the crystals 
which he has produced, which are further illustrated by models and 
diagrams. They are the same as those which were exhibited at the 
Academy of Sciences at Paris, and the liberality of M. Pasteur’s act 
will be appreciated by Members of the Royal Institution, when they 
are reminded that the Paratartaric acid of which they are the 
products is impossible to be obtained, from its having only once been 
accidentally formed, and that these specimens therefore consist pro- 
bably of the only large accumulation of this body in existence. As 
soon as they arrive they will be exhibited to the Members. 
Nevit Story MaskeLyne. 
In the Library were exhibited : — 
An Apparatus exhibiting the colours produced by Polarized Light, 
{by Mr. Newman]. 
Specimens of Pyramidal Alum Crystals, Metallic Arsenic from Cali- 
fornia, Chrome alum crystals — Nitrate of Potash — Tincal or 
Native Borax, and Metallic Antimony [by the Pharmaceutical 
Society]. 
Sanskrit MSS. — Ancient Pictures of Akbar and his Court, and Je- 
hangir and his Court [by the Royal Asiatic Society]. 
‘Models and Diagrams to illustrate a New Theory of Naval Architec- 
ture [by Mr. W. E. Hall). 
