28 AttraSli've Fozvcf of Bodies Jloaiw'g on Water, 



one knows, is an exprefled juice, extends itfelf upon water, 

 as well as the milkv juice of the tiihvmalus and other plants 

 of the like kind, though vifibiv with lefs force; and therefore 

 there is no reafon to doubt that the farina of fruits and other 

 feeds is of the i'ame nature as an exprefled juice, as, both in a 

 hard and fluid ftatc, it extends itfelf on the water in the fame 

 manner as the niilkv juice of olants. The caufe of the greater 

 velocity wiih which farina fpreads ilfclf on water than milk and 

 the milky juice of plants, ought, in my opinion, to be afcribed> 

 Aviihout all doubt, to the rcfinous parts which form a differ- 

 ence between it and milk, as the latter contains a fixed oil. 

 This is the cafe not only in regard to common meal, but alfo 

 In regard to the tuberous roots, all the grafles, and, in ge- 

 neral, all plants ; and befides ihefe, the farina of a great num- 

 ber of feeds of various kinds, both inflammable and incom- 

 buftible, with which I made experiments : mealy fruits have 

 this property in an eminent degree; and on this account we 

 have reafon to aflert that all of them have a fuperabundance 

 of refinous part'icles, and that they muft afford nourifliing 

 food. There is reafon to believe that the refinous part of 

 corn or fruit confilts in the gelatine, and therefore I ima- 

 gined that flarch, as a kind of mucilage, mufl: be deprived 

 of its property of extending itfelf in water; but it, however, 

 poflefl"es that property, though in a lefs degree than meal. 

 We cannot therefore refufe to admit in it a refinous fubfi:ance 

 alfo. It muft, however, be a fubftance more mucilaginou? 

 than gelatine itfelf, or refin ; and we muft afcribc the differ- 

 ence of thefe two fubftances to the proportion of this prin- 

 ciple, and perhaps alfo to its different combinations. 



Ileal gum, when divided into as fmall particles as poftfible, 

 has an extenfive movement on the furface of the water alfo. 

 I therefore confider gum, refinous gum, and refin, to be al- 

 moft degrees of one and the fame fubftance. 



When I was making experiments of this kind with differ- 

 ent fubftances, a thought ftruck me to pound a piece of bread, 

 made of dry grain, and to make experiments with it alfo, in 

 order to ascertain whether it ftill retained the property of 

 meal, and I found that it ftill exhibited the fame pha^no- 

 inenon. This induced me to conclude that the refinous part 

 of meal is deftroyed neither by fermentation nor the procefs 

 of baking. 



Before I quit this fubjeft it may not be fuperfluons to in- 

 form thofe who may wifli to make experiments of this fort, 

 particularly with a view to difcover thofe fubftances which cor\- 

 tain oil or refin, what cautions muft be ufed to prevent them 

 from falling into errors. Their firll carcj then, ought to be, 



that 



