616 EXPERIMENT STATION RECORD. 



the sample after boiliug with acetate for 5 minutes seemed to yield results which 

 were very variable and generally low. 



The method was finally modified as follows : " Transfer 2 gm. of finely pul- 

 verized sample together with 50 cc. of sodium acetate (1:2) to a 500 cc. 

 graduated flasli and boil 5 minutes. Cool under tap, add about 60 cc. of 

 hydrochloric acid (1:3) and shake until solution is effected. Make to volume 

 and filter. Pipette 25 or 50 cc. into an Erlenmeyer flask, neutralize with dry 

 sodium bicarbonate, add 25 cc. of sodium potassium tartrate (1:10) to redis- 

 solve precipitated copper, approximately 3 gm. of sodium bicarbonate, water 

 sutticient to make a volume of 100 cc, 2 cc. starch paste (1: 200), and titrate 

 with normal-twentieth iodin to a permanent blue color. Toward the end of 

 the reaction cork the flask and shake vigorously to insure proper end-point. 

 Calculate results as arsenious oxid. The residue in the graduated flask is 

 brought onto the filter, well washed, calcined in a porcelain crucible, and 

 weighed as insoluble matter." 



The process, according to the author, yields excellent results when used for 

 copper aceto-arsenite, copper arsenite, and calcium arsenite. For determining 

 arsenic acid the author Investigated the Gooch-Browning-Haywood process 

 (E. S. R., 19, p. 310), and modified this as follows : " Transfer 2 gm. of the finely 

 ground sample together with 60 cc. of nitric acid (1:3) to a 500 cc. graduated 

 flask, bring to boil, cool, make to volume, and filter. Pipette 50 or 100 cc. into 

 a 150 cc. Jena Grifiin beaker, add 10 cc of sulphuric acid (2:1), evaporate, 

 heat in an air bath at 150 to 200° C. to expel last traces of moisture, and then 

 on asbestos board to the appearance of dense white fumes to insure complete 

 removal of nitric acid. Add a small quantity of water, and when cold filter 

 through a sugar tube under suction into a 300 cc. Erlenmeyer flask and wash to 

 about 100 cc. Add 10 cc. of potassium iodid (165:1,000) and boil until free 

 iodin is expelled— solution practically colorless — with the reduction of arsenic 

 acid to arsenious acid: A&205+4HI=Asn03+4I+2H20. Dilute, cool imme- 

 diately, neutralize with sodium hydroxid, and render slightly acid with sul- 

 phuric acid. Add starch paste, and if any free iodin remains add dilute 

 (normal-fiftieth) thiosulphate carefully with vigorous shaking to the absence 

 of blue color: 2I+2Na:S203=Na2S408+2NaI. Add excess of sodium bicar- 

 bonate and titrate as usual with normal-twentieth iodin, reporting as arsenic 

 oxid. The residue in the graduated flask is brought onto the filter, washed, 

 calcined, and weighed as insoluble matter." 



Detection of dioxydiamidoarsenobenzol and its difEerentiation from in- 

 organic arsenic in forensic cases, G. O. Gaebel {Arch. Pharm., 2Jf9 (1911), 

 No. 1, irp. 49-56; abs. in Analyst, 36 {1911), No. 421, pip. 153, i5^).— According 

 to the author dioxydiamidoarsenobenzol, which contains 34 per cent of arsenic, 

 gives the Reinsch, Marsh, and Gutzeit tests for arsenic, and it may also be de- 

 tected by a biological test with PenicilJmm glaiiciim. It may, however, be 

 distinguished from the inorganic form with Bettendorf's reagent, which gives 

 with it a yellow amorphous precipitate. The author also points out the readi- 

 ness with which the organic complex in the molecule may be oxidized, and thus 

 serve as a basis for several reactions. 



[Miscellaneous analyses], E. F. Ladd {North Dakota Sta. Rpt. 1910, pp. 

 3Jf-40). — Analyses are reported of cows' and human milks, ammoniated lawn 

 lime and other commercial fertilizer products, ground feed, a potato-bug killer, 

 cement, clays, iron ore, sugar beets, and barley. Tests are also reported of the 

 Illuminating value of three samples of calcium carbid. 



The problem of potato desiccation and its accomplishment by means of 

 cooperation {Internat. Inst. Agr. [Rome], Bui. Bur. Econ. and 8oc. Intel., 2 

 {1911), No. 1, pp. 5-21). — This is a review of the work done in Germany on 



