308 EXPERIMENT STATION RECORD. 



was studied by a new metliod. which Is dynamic and not enzymatic in its action, 

 and consists in raising the, temperature of the digesting solution rapidly when 

 it has arrived at a point near or at its equilibrium. The tests were conducted 

 with a 1 per cent starch solution and chiefly with pancreatln, although in some 

 instances malt and taka-diastases and ptyalin were used as the enzym. 



When the enzym was allowed to act upon the starch solution until a violet 

 coloration was obtained with iodin, and then quickly heated up to 60° or 65°C., 

 a reversion to the original blue coloration of the starch was obtained. No 

 reversion was obtainable after the reaction had proceetied to the achro-dextrin 

 stage, but occasionally dextrin-maltose and maltose-glucose reversions were 

 noted with the polari scope. 



The estimation of iron in milk, G. Fendler, L. Frank, and W. STtJBEB 

 {ZtHchr. Unlcrsiich. Nahr. u. Gcnussmil., J!) {lUlO), ^o. 7, pi). 369, 310).— 

 Evaporate 200 gm. of the milk in a platinum dish and incinerate to white ash. 

 As often the ash still contains some carbon ]iarticles, dissolve the residue (as 

 far as possible) in 5 cc. of hydrochloric acid (specific gravity 1.125) and extract 

 with water. Burn the insoluble particles in the filter completely (with the 

 filter), to the residue add the hydrochloric acid extract previously obtained, 

 and evaporate the whole to complete dryness. Then treat the mass with 20 cc. 

 of fuming hydrochloric acid, again evaporate to dryness, to the residue add 

 30 cc. of concentrated sulphuric acid, digest on the water bath, and finally 

 heat over a burner until dense white fumes of sulphuric acid escai)"es. Finally 

 dilute the residue to 110 cc. with water, filter, and take 100 cc. of the filtrate 

 taken for the Iron determination, which is made in an Erlenmeyer flask. Into 

 the flask place a stick of zinc (around which is wound some platinum wire, 

 the end of which is fused into a glass rod), stopper the bottle with a Bunsen 

 vent and heat for one-half hour on the water bath, allow to cool, remove the 

 zinc stick, and titrate with twentieth-normal potassium permanganate solu- 

 tion. One cc. of the permanganate solution equals 0.004 gm. ferric oxid. 



The so-called "iron milks" examined by the above method, and which 

 were obtained from cows fed iron preparations, contained from 0.0005 to 

 0.00070 per cent of iron oxid, while ordinary milk contained from 0.0004 to 

 0.0012 per cent. 



Determination of sodium chlorid in milk, P. Poetschke (Ais. in Chem. 

 Ztg., 34 {1910), No. 31, p. 268). — On incinerating the residue from milk accord- 

 ing to the usual method some of the sodium chlorid is lost. The author pro- 

 poses to eliminate this possibility by diluting the milk with water, adding 

 copper sulphate, and then allowing sodium hydroxid to run in slowly in order 

 to precii)itate the proteins. The chlorin is determined according to Volhard's 

 method. 



Fat content and specific gravity of curdled milk liquefied with ammonia, 

 O. Hofmeisteb {Landbote, 1910, p. 371; ah.'i. in Molh-. Ztg. [Uildcslieim], 2'i 

 {1910), No. 29, p. 532). — The specific gravity and fat content of curdled milks 

 which were reliquefied with ammonia were determined and the results compared 



with those obtained in the original fresh milk. 



C F 

 The formulas used for this purpose were as follows: For fat. F=-^t — -. where 



A 



F=fat in the original milk, F, = fat in the curdled milk liquefied with am- 

 monia, A=the volume of the curdled milk, and C=the volume of the liquefied 



P g_^ g g 



milk. For the specific gravity, s= ' " . — ' — , where s=the required specific 



A 



gravity of the original milk, Si=the specific gravity of the ammonia. s-=that 

 of the liquefied milk. A=the volume of the curdled milk, B^that of the am- 

 monia, and C=that of the liquefied milk. 

 The results obtained were very satisfactory. 



