362 Annual Report for 191 3 .of the Consulting Chemist. 
all consist, however, essentially of potash in the form of 
chloride, together with varying amounts of sulphate of 
magnesia and common salt. 
The presence of magnesium chloride in any considerable 
amount constitutes an objection as tending to cause the salts to 
take up water and become deliquescent. Consequently it has 
been usual to classify the salts according to the amounts of 
potash and magnesia severally contained, and to designate 
them by special names. Sylvinit , for example, is chloride of 
potassium with rock salt (chloride of sodium) but with very 
little magnesia salts ; carnallit , on the other hand, is a low 
quality of chloride of potassium with considerable amounts of 
chloride of magnesium, and also sulphate of magnesia together 
with chloride of sodium ; kieserit is practically sulphate of 
magnesia alone, and hartsalz (hard salt) is chloride of 
potassium with chloride of sodium and about 9 per cent, of 
magnesia, this being present mainly as sulphate of magnesia. 
It is the sylvinit (chloride of potassium with chloride of 
sodium, and with very little magnesia) and the last named salt, 
hartsalz , which are now principally produced and sold in 
commerce under the name kainit. The export of the different 
salts takes place from different sea ports, and so there may, 
from time to time, be variations, sometimes more of one kind 
and sometimes more of another coming forward. 
In these ways come about the variations which purchasers 
sometimes note, and which render them doubtful as to what is 
being supplied, thereby making them think that perhaps an 
inferior article is being palmed off. 
It is well, therefore, to point out that there is really nothing 
essential in the particular colour or appearance of the salts, and 
that if the amount of potash, be guaranteed (as is the rule in 
the trade), and provided that the salt is in fair dry condition 
and does not deliquesce, the colour may be disregarded. 
What, however, s essential is that the supply, under the 
name of kainit, of salts which, like carnallit , contain large 
amount of magnesia salts (chiefly as chlorides) should be 
avoided, though these may contain 9 to 10 per cent, of potash. 
Not long ago an attempt was made to introduce the use of 
these, they being sold on their potash contents alone. These 
salts, by reason of the chloride of magnesium present, soon 
became very moist and deliquescent, and great difficulties were 
experienced in storing and in using them. 
Carnallit should never be offered as kainit, for the two salts 
are essentially different, and the purchaser should stipulate for 
kainit and should buy on the base of its containing 12 to 12\ 
per cent, of potash. Yet other forms of potash salts require to 
be guarded against. One of these is a salt artificially prepared 
