GERBER'S FAT DETERMINATION 209 



The fnllowinu' appliances are necessary for this examination (t^ee 

 Fig. 20): (1) three pipettes of 200, 60 and 10 c.c; (2) several 

 half liter bottles; (3) two delicate areometers with thermometer, 

 one t'(ir whole milk and the other for skimmed milk; (4) one large 

 trlas- tube (A) adjusted for flowing water; (5) a smaller glass 

 tube (B) enclosed in A; (6) a rubber bulb with a tube; (7) a larger 

 conlaiiier lilled with water heated to 17° to 1R° C. Besides these, the 

 following' chcjuicals are necessary: (S) potassium hydroxide solution 

 of specitic L;i-avity 1.27 (400 ^r. potassium hydroxide is dissolved in 

 watei- and after the solution has cooled it is made up to 1 liter) ; (9) 

 ether, shaken with one-tifth its volume of water and decanted off; 

 (10) ordinary ether. 



The milk to be examined is warmed in a water bath to ls° (.'. and 

 is well shaken. By means of a pipette, 200 c.c. of this are drawn 

 off and nuxed in a bottle witli 10 c.c. of the pota.ssium hydnixide 

 solution. Then, 60 c.c. of ether are added. The bottle Ls immediatelv 

 closed by a perfectly tight st(jpper, is violently shaken and allnwed tn 

 stand iiiie-tiiurth hour- in water at 1S° ('., during which time it mast be 

 shaken frequently. Gradually, the ether dissolves the fat and a 

 transparent layer is formed on the surface. Xnw the stop])er of 

 the bottle is replaced by another (D) and, liy means of a bulb, the 

 transparent fat-containing ether is driven up into the tulie B which is 

 surrounded in tube A by water warmed to 18° i\ The areometer 

 ((') is in the inner tube, and after the fluid rises so high that it 

 can float, the flow is checked by means of a valve q, then the 

 specific ^lavily is read. The quantity of fat dissolved is shown, and 

 from this the fat content of the milk can he calculateil. Snxhlet's 

 apparatus Ls accompanied by tables from which the fat content of the 

 milk can easily be read, if one has determined the specitic gravity 

 of the fat-ether, and lias read its temperature. 



(iiihci's (icidobiiti/roinctcr affords a vei'v conveuieiit 

 and accurate way of determining fat, that is widely 

 used. The method consists in measuring the quantity 

 of fat in an accurately measured quantity of milk, after 

 the fat has been separated and dissolved in amyl-alco- 

 liol. Gerber's instrument (see figs. 21 and 22), consists 

 of a centrifuge, bottles (G) of special shape, and 3 

 pi]icttcs, /.<■. : 1 acid pipette to hold 10 c.c.(H) and 2 small 

 pipettes (T, K) of 1 and 11 c.c. capacity. These eliem- 



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