BULLETIN OF THE BUSSEY INSTITUTION. 367 
in truth; but it is a little remarkable that the notion should have 
gained such currency as it has, in view of the fact that most potas- 
sic fertilizers sold as ‘‘ sulphates” are really highly charged with 
chlorides, and are presumably subject to all the objections which 
would apply to the chlorides properly so called. Mayer remarks, 
however, that the change from chlorides to sulphates marks an 
epoch in the history of the sale of fertilizers at Stassfurt, — kainit 
being more and more used in recent years, instead of carnallite as 
formerly. In pot-experiments, made for the purpose of compar- 
ing chloride and sulphate of potash (the pure salts being used in 
both cases), Mayer got decidedly better crops of clover, millet, 
and tobacco with the sulphate ; but in the case of grain there was 
no important difference between the two results. The soils used 
in these experiments were poor, and they were for the most part 
dressed with phosphatic and nitrogenous fertilizers in addition to 
the potash-salt. The fact, repeatedly verified, that the potash in 
- chloride of potassium is not arrested, i. e. ‘‘ fixed,” so speedily by 
the earth as potash which is applied in the form of sulphate would 
seem to show that the chloride might sometimes be specially use- 
ful as a means of distributing potash throughout a soil that hap- 
pens to be pretty thoroughly exhausted of this particular form of 
plant-food ; but, as has been intimated above, the substances ordi- 
narily sold nowadays as sulphate of potash are abundantly able to 
serve this purpose, thanks to the chlorides that are contained in 
them. They are doubtless on this account better suited for such 
work than pure sulphate of potash would be. 
As bearing on the use of sulphate of potash, it is worthy of rec- 
ord that some of our farmers were subjected to serious damage and 
annoyance a few years since through having put upon their fields 
an acid product which had been sold to them either as ‘‘ sulphate 
of potash,” or in disguise as an ingredient of some one of the so- 
called formula fertilizers. The substance in question was the ses- 
quisulphate of potash, which results from the making of muriatic 
acid by distilling Stassfurt muriate of potash with sulphuric acid, 
— a process of manufacture which, as I urged some years since,* 
is clearly indicated as a proper one for the American seaboard 
states. But it is in some sort a necessity in this process of manu- 
facture that an excess of sulphuric acid shall be used, over and 
above what would be necessary for converting the chloride into a 
neutral sulphate, in order that the residual ‘* cake” may melt read- 
* Bussey Bulletin, 1. 185, note. 
