yours, barring your process." These experiments were made at his
country residence. I was staying there for the night. So next morning
I got down before him, went at my experiment, saturated 8 oz. of acid
(and a nice smell I made) out in the grounds, treated it afterward by
division into four parts, filtered and crystallized it, all as before,
with the result that I obtained 2¾ oz., as against his 3½ oz.--or in
the proportion of 27½ cwt. of salt to the ton of acid, as against his
32½ cwt.

I now thought of business. "What is the royalty to be?" I said, as we
sat at breakfast. This we settled as we Scotch say "in a crack," or as
an Englishman would say "in a jiffy." Mr. Croll decided to have the
apparatus put up on a manufacturing scale here in Glasgow; and I
determined to erect similar apparatus at one of my gas works.

I dare say that it will be uppermost in your minds, Whence comes the
increased yield of salts? Well, I will state one fact, and leave you
to ruminate on it, namely, by Mr. Croll's process we did not seem to
produce any sulphureted hydrogen. The experiments were conducted in a
room with ordinary doors and windows, but without a chimney; and we
were not troubled with any offensive smell--a state of things that
could not possibly have existed had we been experimenting with any
other apparatus hitherto employed in the manufacture of sulphate of
ammonia. The apparatus, which will presently be described, only
substitutes, for the present mode of distillation, a new one, which
forms the subject of Mr. Croll's patent. All other parts of present
apparatus can remain as they now exist.

Mr Croll has also introduced another mode of producing sulphate of
ammonia, which dispenses with all the apparatus hitherto in use after