FOURTEENTH ANNUAL MEETING. 137 



as successful results as our own, due in part perhaps to differ- 

 ent methods employed, and as a consequence we are indorsing 

 these washes to the exclusion of almost anything else. 



A number of investigators have made repeated attempts 

 to studv the chemical character of lime-sulphur washes and 

 thus gain an idea of the essentials necessary in controlling the 

 San Jose scale. Unfortunately the chemistry of lime sul- 

 phides appears to be almost unknown ground, and as a con- 

 sequence entomologists have obtained very little satisfaction 

 from chemists. It may be remembered that the original lime- 

 sulphur salt wash is said to be a sheep-dip which, when the 

 sheep disappeared in the West, was applied to trees with ben- 

 eficial results. We have been considerably interested in the 

 chemistry of this wash because we could not help feeling that 

 the combination might be modified to advantage, and not be- 

 ing a chemist and unable to obtain much help from chemists, 

 we adopted the other alternative and studied the wash in a 

 practical way. In the first place, we figured out a number of 

 formulae and had washes prepared in the laboratory, observ- 

 ing the results closely and using them as a guide to larger 

 outdoor operations. One of the old lime-sulphur-salt washes 

 called for 40 lbs. of lime, 20 lbs. of sulphur and 15 lbs. of salt 

 to 60 gallons of water, and the authorities insisted upon boil- 

 ing from one to two or even three hours. A study of this 

 formula convinced us first of all that there was a very large 

 excess of lime. Laboratory experiments showed that we ap- 

 parently obtained just as good a combination when consider- 

 ably less lime was employed, and field work not only sup- 

 ported this conclusion, but showed that there was less danger 

 of the dry wash scaling or peeling off when the smaller 

 amount of lime was employed. The question also arose as 

 to the efffcacy of salt, and upon trying washes without this, 

 we obtained just as good result? as though it were present, 

 'consequently we do not recommend its employment. The 

 prolonged boiling and diluting with hot water required by the 

 old formulae made the preparation of this wash very laborious, 

 and our laboratory experiments again showed that so far as 

 color, indicating the relative proportion of the sulphides, was 

 concerned, a very good combination was effected in thirty 

 minutes' active boiling. It will be interesting in this connec- 



