Annual Report for 1913 of the Consulting Chemist . 361 
l 
better quality and more reasonably sold, did not possess, but 
that tliis was really a case of “ rival traders,” and that the issue 
tried was whether those who had attacked the low quality of 
slag had not overstepped the limits of fair comment in the 
circulars which they had issued. The trial in question did no 
more than show that, so far at least, the prominence attached 
by some traders to the high solubility of their slags had not 
been established in practice as against the “total phosphates” 
content. At the same time, the award in this case does 
not warrant the verdict being claimed as affording a vindication 
of a low quality basic slag being sold at what must, on the face 
of it, be considered a relatively high price. 
Kainit is a material which has long, and deservedly, been 
in use by the agriculturist. It, in common with other salts of 
potash, some of them natural, some prepared by crystallisation 
and refining, was obtained originally from the mines in 
Stassfurt, North Germany, where the different natural salts 
occur in beds overlying one another, and each known by a 
particular name according to its nature and chemical composi- 
tion. Kainit is one of these, and is a natural, and not a 
prepared, salt. 
About its exact chemical composition there has always been 
considerable uncertainty. At first, the pure salt was regarded 
as composed of sulphate of potash with sulphate of magnesia 
and chloride of magnesium, and the formula K 2 S0 4 , Mg S0 4 , 
Mg Ci„, 6 H 2 0 was assigned to it, as indicating that the potash 
occurred in the salt as sulphate of potash. This view was, 
however, controverted, and later researches tend to the belief 
that the potash is really present, not as sulphate but as chloride 
(muriate), and the formula KOI, Mg S0 4 + 3 H 2 0 was given 
to it as more nearly representing its composition. This, with 
more or less chloride of sodium (rock salt), constitutes the 
kainit of commerce. 
Among agriculturists in this country kainit has generally 
been regarded as a crude form of sulphate of potash, containing 
about 12 per cent, of potash, equivalent to about 23 per cent, 
of sulphate of potash. It would seem, however, that this is 
hardly correct, and that in the kainit supplied for agricultural 
use the potash has really always existed as chloride and not as 
sulphate. 
As the potash-mining industry has extended, and wider 
reaches of country have been explored in which the beds of 
potash salts are still existent, certain variations in the quality 
and composition of the different gaits found has necessarily 
been met with, and these have had their effect in somewhat 
modifying the nature, and, to some extent, the appearance, of 
the salts put on the market under the name of kainit. These 
