AGBICULTURAL CHEMISTRY AGROTECHNY. 411 



10 cc. of a 0.3 per cent hydrogen peroxid solution and 25 cc. of the iron- 

 ammonium citrate solution are added. The mixture is then stirred at a tem- 

 perature of from 15 to IS" C. After the stirring apparatus has been brought 

 into full operation, 25 cc. of magnesia mixture is added, and after stirring for 

 one-half hour, it is filtered. 



The method as given yields the same results as those given by the German 

 Association method (removal of silicic acid by evaporation with hydrochloric 

 acid), the Darmstadt method (elimination of silicic acid by heating with citrate- 

 magnesia mixture), Naumann's method, and the molybdate method. The dis- 

 advantage of using the Lorenz method is pointed out, and some comparative 

 results obtained with the Lorenz and the direct method are given. They agree 

 very well. 



Technical caseins, their examination and judgment, W. Hopfnkr and H. 

 BuEMEiSTEE {Cliem. Ztg., 36 {1912), No. 112, pp. 1053, 105.',).— A discussion in 

 regard to the criteria to be utilized in judging caseins destined for food, sizing 

 of paper, etc. The most appropriate methods are described. 



An improvement of the method for the determination of galactan, K. 

 MiYAKE {Jour. Col. Agr. Tohoku Imp. Univ., 4 {1912), No. 8, pp. SSl-SltS).— 

 This is an improved method for determining galactan in foods and feeding 

 stuffs, as follows : 



" Take a given quantity of the substance to be examined, extract with ether, 

 and place the residue in a beaker together with nitric acid, and evaporate the 

 solution in a water bath exactly in the same manner as recommended in the 

 'provisional method' [A. O. A. C] referred to. Filter hot immediately 

 after evaporation and wash well with hot water. The filtrate is again evapo- 

 rated down to one-third volume of the original solution. After allowing 

 to stand 24 hours, add 10 cc. of water and allow it to stand another 24 hours or 

 longer if necessary. In the meantime the mucic acid will be crystallised. 

 Collect the mucic acid on a tared filter or Gooch, wash with cold water, then 

 with alcohol, and finally with ether; dry at the temperature of boiling water 

 and weigh. 



"The amount of the sample to be taken for analysis must be determined 

 according to its galactan content. If its content is below 16 per cent on dry 

 matter basis, 3 gm. can be taken, but if more galactan is contained, then a 

 correspondingly smaller amount of the substance must be used, as otherwise 

 the mucic acid is liable to crystallize out before the filtration. On the other 

 hand, if the amount of galactan is insignificant, and below 0.8 per cent, the 

 filtrate should be evaporated down into one-fifth its original volume, and 

 allowed to stand several days if necessary ; otherwise the mucic acid may fail 

 to crystallize even after long standing, and it may lead to an erroneous con- 

 clusion." 



The estimation of methyl alcohol in ethyl alcohol and in alcoholic drinks, 

 A. Bono {CUem. Ztg., 36 {1912), No. 121, p. 1171, fig. 1).—A fiescription is given 

 of an apparatus to be used in connection with a method in which the methyl 

 alcohol is oxidized into formaldehyde with potassium bichromate and sulphuric 



acid. 



Estimation of the amino acids in plants by means of the formaldehyde 

 method, O. Batixy {Bui. Sci. Pharmacol., 18 {1911), No. 12, pp. 702-711; abs. 

 in Chem. Zentbh, 1912, I, No. 20, p. 16 ',0 ; Analyst, 37 {1912), No. 436, pp. S12, 

 S13),—U the aqueous extracts of plants are first treated with barium chlorid 

 for the purpose of removing phosphates, and tlie color is removed with quinin 

 silicotungstate, the amino acids present in the extract may be estimated by the 

 formaldehyde titration method- 



