41 



oleates of 1 to 4 of water to a soap made with soda and stearates of 

 above 1 to 40 of water. 



The first explanation that suggested itself of the difference in the 

 behavior of the various insecticide soups tested was the very natural 

 one, under the supposition that they were fish-oil products, that it was 

 due to the manufacture of the snaps in some instances with potash and 

 in others witli soda, the former being liquid in solution and the latter 

 solidifying. The chemical examination of these soaps, however, failed 

 to support this theory and showed that in every case the soaps exam- 

 ined had been made with soda with the single exception of the one 

 made at my special request by Good with potash. Many of these soda 

 soaps, including the Leggett whale oil, were thoroughly satisfactory 

 with the solution test, The correct explanation undoubtedly is that 

 the solidifying of certain brands of soaps is due to the admixture with 

 fish oil, if the latter be used at all in these instances, of more or less 

 waste beef or mutton tallow. It may be possible that there are other 

 reasons for this condition which have not been discovered, but the 

 above seems to be the important one. The result of the chemical 

 examination and physical test seems to indicate one thing at least, that 

 whether made with soda or potash, if fish oil, which is almost wholly 

 olein, be used the product will stand satisfactorily the solution test. If, 

 therefore, Ave can have a guaranty that a soap is altogether fish oil and 

 properly made, the kind of lye employed is not absolutely essential, 

 although the potash product is the more desirable. 



The statement made in a former communication on the subject of 

 soaps that very little water would enter into the composition of a well- 

 made article is confirmed by these analyses, made by Professor Patrick, 

 which show an average of less than 20 per cent water, and with the 

 better brands between 10 and 15 per cent, the balance being the lye 

 and fats. 



The result of the investigation of this subject indicates that a fish 

 oil or other oily soap should be invariably demanded and the desirability 

 of giving a sample of the soap secured from a manufacturer a solution 

 test before purchasing on a large scale, or preferably demanding a prod- 

 uct which will stand such test. The determination of water constituent 

 of soaps is difficult and can ordinarily only be made satisfactorily by 

 chemists, and while desirable for accurate work may perhaps be ignored 

 if the soap is a good, firm one and stands the solution test properly. 

 It would seem also advisable to have the station chemists of the different 

 States empowered to inspect and certify the qualities of any soap man- 

 ufactured and sold for insecticide purposes. 



In discussion, Mr. Fernald referred to the statement of Mr. Marlatt 

 that poisoned foliage seemed to be repugnant to larva 1 , and stated that 

 the experience of the gypsy moth committee did not seem to bear out 

 this view. He called on Mi-. Kirkland to give the facts as brought 

 out in the work of the gypsy moth committee. 



