utilisntioii of fiits i n c d i l h protliicts ( h t t c r , iiinrgnrinc, cooking fnts, confcct.ioticry), for. soapintiking, in paints niid vnriiislics, or for other purposcs itivolvcs nt tho present timc the consuq)tion of scveriil niillion tons per year of iintnrnl ints iinrl thc existnice of very Inrgc industries, ciiiploying Irirge numbers of people, which nrc tlcpciident on tlic natural fnts ns rnw nintcrinls.
Tlicre nre many diffcrcnt kinds of fats iii\d fatty acids foulid botJi in tlic fruit of plntits rind in n~ii~nals, some solid, sonic liquid, others semi-sdid ; of the solid fiits, soiiic are very linrcl nntl Lrit,tlc, otlicrs, evcn though t h y niclt. n t n Itighcr tcmlicriiturc, arc softer mid iiiorc plnstic in tcxture ; and of tlic liquid fnts (or oils), soiiie will kccp iiiorc or lcss utiiiltcrctl on storngc, whilst others bccoiiic gutnitiy or tl~ickct~ on csposurc to nir. suitnblc for hitter or lnrtl sul)stittitcs or for other ctlil~lc ends, obher fnts itscfiil ns sot~p-~iialii~ig nintcrinl, nud yet IJtllCI'S (" drying '' oils) iid~il)t~(l to iisc in the p-epnrntioii of piiints. A nua~bcr of niorc or less rnpiil nnii1yt.icnl tests linvc been tlcviscd I J ~ ineit~is of which those cngngetl in t,hc protluction of any of tlwsc cominoditics cnii rentlily ~S S C S S the utilit,y of iiny givcii Iintl1riil fat for their piirtic~lnr service, hit tcchiiical nnnlyrical ltlethotls of this 11nttnt do ]lot, ils n I&, tell US \*cry J t l U C h i l b O U t the ChCltliCtl~ S t ~l l C L l l l ' C of thC fats. S C V C rtliclcss, the uscfulncss of n pnrticulnr Int dcpciids u1t.iniiitcly on its fuiidaiticntnl clicitiic:rl structurc, itnd it is tlicreforc dcsiriiblc to liiive ;is cotnplcte kiio\vIcdge of