436 
Ahitrad Report of Agricultural Discussions, 
preventing incrustation, Mr. Amos said, that althongh he had had 
no experience of it himself, a friend of his was well satisfied with 
its action. 
Professor Wilson, after stating, that he did not, at once, see how 
caustic soda would act, said, A few years ago a foreign chemist re- 
commended chloride of ammonium (the common sal ammoniac) for 
preventing the furring of boilers by calcareous deposits ; and the 
action of this substance is quite intelligible, because when it comes 
in contact with the salts of lime a double decomposition takes place ; 
the chlorine of the sal ammoniac goes to the lime and forms a solu- 
ble salt of lime, whilst the carbonic acid of the carbonate of lime 
goes to the ammonium, forming a carbonate of ammonia, which 
passes off with the steam without doing injurj'. The action of the 
sal ammoniac is therefore quite intelligible. It is rather expen- 
sive (9c?. to Is. per lb.), but the cost is as nothing when compared 
with the injury and inconvenience against which it is a protection.* 
Sir E. Kkkrison said, in the case of the boiler of a fixed engine, 
one of several which he had at work, a deposit was formed an inch 
thick, which had to be removed with hammer and chisel. The 
boiler was not only dangerous, but it had ari-ived at such a state 
that it was almost impossible to supply sufficient heat for working. 
The amount of fuel which was necessarj' was nearly doubled. He 
had applied in vain to a distinguished engineer for a means of 
preserving boilers from incrustation, and intended to try the 
caustic soda. 
The desirability of establishing a society for the periodical in- 
spection of .steam boilers used for agricultural purposes was enforced 
by Mr. Dent, M.P., Mr. Amos, and Mr. Hobbs (the Chairman). 
Mr. Spiller in the following letter has further explained the 
action of caustic soda : 
" Royal Arsenal, Woolmch, August 12, 1862. 
" Since the date of the Society's Meeting in March last — at which Mr. 
Holland, M.P., did me the honour to communicate a memorandum on the 
subject of the employment of caustic soda for boilers — I have received and 
answered numerous inquiries from correspondents who have been anxioias to 
know more of the nature, mode of action, and cost of the material emploj'ed. 
Under these circumstances, I gladly avail myself of an opportunity of making 
a fuller explanation in regard to my own and other propositions which were 
then laid before the Society. 
" The visitor to the International Exhibition will find in Class Tl. (Chemical 
Products) several excellent samples of commercial cau.stic soda from manufac- 
tories in Liverpool, Newcastle, Warrington, Glasgow, &c., priced from 
14Z. 10s. to 111. per ton. In smaller quantity, the same article may be pro- 
cured, at a slightly advanced price, from Messrs. Baiss Brothers, chemists, of 
Leadenhall-strcet, London. The properties of caustic soda are such that to 
keep it dry it requires to be well protected from the atmosphere ; but, inas- 
much as it will always be used in the .state of solution, we arc in the habit of 
* Mr. Spiller lias called attention to the injurious action of this substance on the 
boiler.— P. H. F. 
