ELISHA MITCHELL SCIENTIFIC SOCIETY. 15 



and that there seems to be a power of selection on the ])art of 

 the plants, some having no affinity for and not takino- up the 

 boracic iwk], though growing on the same soil from which other 

 plants absorb it. We are forced to the belief that it is contained 

 in the soil and that the plants draw it from that source, yet in 

 no case could I detect its presence in the soil, and in no well 

 water examined could I get a test for it. It is easily possible 

 that other waters might contain it. It would be of great int(!rest 

 to extend this examination of natural waters so as to see whether 

 the boracic acid in the soil is in a soluble form or not. It may 

 be present in a form soluble in plant solvents and insoluble in 

 natural waters. Of course it is possible, also, that it is present 

 in such great dilution that the amount of water evaporated failed 

 to give the qualitative tests. My examination of different fer- 

 tilizing materials revealed the fact that several of the commonest 

 contained boracic acid in appreciable amounts, and hence, by this 

 means, it is being constantly added to soil under cultivation. 



Of course stable manure, coming from grain and straw, 

 restores to the soil the boracic acid contained in these. 



A further important fact brought out by this research is that 

 every sample of caustic alkali examined contained boracic acid. 

 These samples were from the best known manufacturers, and 

 were marked chemically pure. As these alkalies, especially 

 potassium hydroxide, are used in most of the methods for deter- 

 mining boracic acid, it is manifestly of great im})ortance to secure 

 them free from it as an impurity. I think it possible that the 

 boracic acid in these samples, or at least in some of them, mav 

 have come from the glaze of vessels used in their manufacture 

 or from the bottles containing them. 



The method of testing was that used by Meisell for the detec- 

 tion of boracic acid in milk.* About one gram of the ash was 

 treated with strong hvdrochloric acid and boiled a few minutes 

 to insure solution. It was then filtered from the unburnt car- 

 bon, insoluble silica, etc. The filtrate was evaporated to dryness 



*Konig's Nahrungsmittel, 2, 250. 



