417 
LEEDS CHEMISTS’ ASSOCIATION. 
The Third Meeting of the Session was held in the Library of the Philosophical and 
Literary Society, upon the evening of December 14, 1864; the President (Mr. Ilaigh) 
in the chair. 
Mr. Wm. Smeeton was elected a Member, and Messrs. Paine, Fowler, Wilson, Norrish, 
Dobell, and Ball were elected Associates. 
Donations of Books to the Library were announced from Messrs. Barber, Church, 
Draper, Haselden, and Squire, for which the best thanks of the Association were voted 
to the donors. 
Mr. R. Parkinson, Ph.D., of Bradford, (a Corresponding Member) read the paper of the 
evening, which was fully illustrated by apparatus and experiments. 
By Volumetric Analysis is meant a system of analysis by measure, as distinguished 
from the older and generally understood methods, in which the various constituents of 
the substance under examination are obtained in a separate form, and are then weighed. 
The distinction between the two methods may be also thus expressed:—in the older 
system, that of analysis by weight, or “ the dry way,” we endeavour to ascertain the 
quantity of material which is produced by any reaction, while in analysis by measure, or 
“ the wet way,” we generally take no notice of the material produced, but base our 
calculations on the quantity of reagent used to produce certain results. These by the 
laws of chemical combination are convertible terms, and in most cases convenience and 
simplicity are on the side of analysis by measure. Thus, in estimating the quantity of 
sulphuric acid present in any substance by the old method, we have to precipitate it by 
means of baryta, taking care only to add more than is absolutely necessary, then the 
resulting BaO, S0 3 is collected and weighed, and from its amount that of the S0 3 is calcu¬ 
lated. By the newer method we take no notice of the quantity of BaO,SG 3 that is pro¬ 
duced, but we carefully ascertain the quantity of Ba 0 that has been required to produce 
it. A slight variation in the calculation then brings us to the same result. 
Although volumetric analysis has been much improved and extended of late times, 
yet it does not in many cases supersede the older methods, as there are certain conditions 
required for its use, and whichare not always capableof fulfilment. Its principal advantage 
consists in the very much less time required for its operations than when the various 
substances have first to be separated in a convenient form, then washed or otherwise 
purified, dried, and finally weighed. Under the old system you have first “ to catch your 
hare, then cook it,” and finally dispose of the same, whereas, under the new, you may be 
said to eat your hare without either catching or cooking. As one instance of the saving 
of time by analysis by measure, I will suppose that we require to know the value of, 
that is the amount of iron contained in, a sample of iron ore. Under the old system we 
must dissolve the ore in HC1, filter, and precipitate the Fe 2 0 3 by means of NH 3 , collect 
this precipitate on a filter, wash till quite free from soluble matter (no easy task) then 
dry, and finally weigh. These operations will take the best part out of a day’s work. 
Now, on the other hand, we dissolve in acid as before, boil a few minutes with zinc, dilute 
with water and add a solution of KG Mn 2 G 7 until a red colour is produced. The amount 
of permanganate used will then (if the solution has been properly prepared and the 
quantity of ore taken be in correspondence) at once give us the percentage of iron. This 
can all be done in half an hour, or in an hour easily. Again, it may be required to know 
the alkaline value of a sample of soda ash, an article that often requires its true value 
finding. By the old methods, this could only be done by a very tedious process, while 
“ alkalimetry,” which is the name given to volumetric analysis as applied to the estimation 
of alkalies, will furnish the desired result in a few minutes. 
Before proceeding with any of the manipulatory details, it will be well just to notice 
the principles on which the capabilities of volumetric analysis depend, a clear under¬ 
standing of which is necessary to its intelligent appreciation, and without which it cannot 
be carried out successfully. Some branches of it are indeed so simple, that even the 
most ignorant may arrive at results, if supplied with materials and apparatus, with 
empirical directions for their use. Such must, however, always go in the same groove, 
and will be unable to rectify any error. Powers of this kind are worth very little ; it 
behoves all, therefore, to make themselves acquainted with its principles, of which, 
perhaps, the first and greatest is the law of equivalents, or the law of combination in 
definite proportions, especially that part of it which is implied in the name “equivalent ” or 
