New York AgricutruraL ExpreriIMeNT STATION. 3855 
INTRODUCTION. 
‘The chemical investigation of the so-called lime-sulphur 
wash, the results of which are given in this bulletin, was under- 
taken in response to numerous inquiries that were coming to 
the Station in increasing number. Many of the questions 
called for chemical knowledge and there were frequent consul- 
tations between the Entomologist and the Chemist of the 
Station. At the request of the former, it was decided to un- 
dertake a study of some of the fundamental points connected 
with the chemistry of the lime-sulphur wash. To meet the con- 
ditions, the investigation has been directed along two gen- 
eral lines: (1) A study of the details of the operation of 
making the lime-sulphur mixture, and of the composition as 
influenced by conditions of preparation; (2) a chemical exami- 
nation of the commercial preparations that have been exten- 
sively purchased by fruit-growers. 
In connection with the first point, it may be stated that many 
who had been preparing the mixture at home failed to secure 
a uniform product at all times, and, consequently, the results 
of the applications varied greatly at different times. In con- 
Sequence of this lack of reliable uniformity, many became dis- 
couraged and lost all confidence in home-made preparations, 
especially the concentrated forms. They were then in a frame 
of mind to make use of commercial preparations. These had 
not been used long before questions began to be raised about 
the efficiency of one brand as compared with another. For ex- 
ample, some preparations were clear, free from sediment and 
retained this condition a long time; some were full of an olive- 
green, muddy-looking sediment and some, on standing, became 
filled more or less in time with crystalline deposits containing 
much sulphur, weakening to that extent the solution of sul- 
phur compounds. These differences could not fail to attract 
attention. The manufacturers of the brands that contained 
much sediment claimed, without proof, that this muddy, solid 
matter really added to the effectiveness of the mixture as a 
scalecide, while the contrary claims were made by manufac- 
