EXPERIMENT STATION BULLETINS.. 277 



more speedy dilution, especially in cold weather. I have always placed 

 soft soap first, as most farmers have it; and convenience is very important 

 in such matters. A farmer will make and use an article when all the ingre- 

 dients are at hand, whereas he would not do so had he to go and purchase 

 them for this express purpose. 



The agitation should be violent, but need not be long. We have formed 

 a perfect emulsion in one minute even with cold water. 



The Hubbard-Riley formula is as follows: One half ft), of soap, dis- 

 solved in one gallon of boiling water, when two gallons of kerosene are 

 added and immediately stirred as before. It will be seen that I use four 

 times as much water as kerosene, while Dr. Riley recommends twice as 

 much kerosene as water. I also use more soap. 



THE TWO EMULSIONS CONTEASTED. 



My recipe never fails with us to produ3e a perfect emulsion. It will 

 even emulsify with cold water, if the soap is thoroughly dissolved. I have 

 made perfect emulsions repeatedly with cold water; and have repeated it 

 .several times this winter. I prefer a hot solution as the soap is more 

 quickly dissolved. 



Dr. Riley's formula often fails; I think it has failed with us in at least 

 forty per cent, of our trials to emulsify at all. It must be very hot. Prof. 

 Gillette says that he often heats the oil, which I should hardly wish to 

 recommend, and any hitch in the stirring after adding the oil is fatal to 

 success. Prof. Gillette adds, in a private letter, that he has had fail- 

 ures with this, and urges three cautions: 1st, good soap, like Ivory. 2d, 

 a boiling temperature upon adding the oil, which must not be too cold ; and 

 3d, everything must be clean. With my formula he would not have to 

 urge any of the above. 



While the kerosene is thoroughly emulsified in my preparation, the 

 emulsion, owing to* the excess of soap solution, often separates from the 

 remaining liquid upon standing, especially if made of soft soap, rising 

 above the soap solution. This is also true of the dilution; but there is no 

 free oil; this is probably what deceived Dr. Riley and Prof. Gillette. 

 They saw this separation, and thought the liquid was not emulsified. Had 

 they tested the diluted emulsion by putting a small piece of paper on top, 

 and then touching the latter upon removal, with a lighted match, they would 

 have quickly found that it was a perfect emulsion. The readiness with 

 which it mixes, upon slight shaking, even years after preparation, is further 

 proof. I have some in our museum made years ago, that is a perfect 

 emulsion to-day. It is that pronounced against by Dr. Riley. One who 

 has had much experience will be at no loss to distinguish a perfect emul- 

 sion as soon as he adds water to dilute it. If there is free oil it will not 

 mix; if not, it mixes very readily and with very slight agitation. 



Dr. Riley's emulsion thickens completely, looking like thick cream. 

 This makes it hard to handle, especially in winter, as it must be dipped 

 and can not be turned from a vessel; but, more, the viscid mass hides the 

 imperfection of the emulsion so that it does not appear till dilution takes 

 place. The diluted emulsion also is more uniform upon standing, except 

 that in all our experiments free kerosene rises to the top, which is less in 

 •case soft water is used. 



Again, my preparation is thoroughly emulsified so that upon any dilu- 

 tion, even with hard water, no free oil rises to the top. Thus it is easily 



