612 EXPEEIMENT STATION KECORD. 



describetl in full, and tho results obtiiiiifHl with (he ]nc4hod and othor nietliods 

 and slaf^s of widely varyii'n conii'osilion are ^iven. The figures given by the 

 I'upp method conijtared well witii those by the other methods. 



Some work conducted at other experiment stations Avith the new iron citrate 

 method and other methods (old iron citrate, hydrochloric acid, Naumann, and 

 von Lorenz methods) is also reported. The results in general confirmed the 

 author's conclusions in regard to injurious silicic acid. The new iron citrate 

 method, when compared with the Naumann and hydrochloric acid methods, 

 seemed to give the best result. The von Lorenz method on the average (100 

 analyses) gave 0.28 per cent less phosphoric acid than the Ts'aumann method, 

 and 0.2r) ])er cent less than the hydrochloric acid method. 



A field method for determining' dissolved oxygen in water, J. ^Iilleb 

 {Jour. 8oc. Cheni. Indus., 33 (lOIJ/), No. -'/, pp. 185, 186). — The method adopted 

 is as follows: 



"To 50 cc. of the water contained in a 100 cc. Nessler cylinder is added 5 cc. 

 of alkaline tartrate such as is used for Fehling's solution and one drop of 

 phenosiifranin solution (1 in 2,000 of water), then from a 10 cc. graduated 

 pipette a solution of ferrous sulphate (0.22 gm. of pure FeSOi and 1 cc. of 

 concentrated sulphuric acid in 100 cc.) is run in just below the surface of the 

 liquid, stirring gently with the pipette until the color is discharged, looking 

 through the cylinder horizontally. The ferrous sulphate is added 1 cc. at a 

 time until the color begins to fade, then in additions of 0.5 cc. to the end. 

 There is a slight coloration at the surface of the liquid, but if the stirring is 

 not too vigoi'ous this does not interfere. The outlet hole of the pipette should 

 not be more than 1 mm. in diameter to minimize diffusion. 



" The pipette reading gives the cubic centimeters of oxygen per liter. Theo- 

 retically 1 cc. ferrous sulphate of above strength does not equal 1 cc. oxygen 

 per liter working on 50 cc. of sample (0.25 per cent FeSOi is theoretical 

 strength), but under the conditions stated I have fomid that the above strength 

 gives correct results. 



" Each experimenter should standardize his ferrous sulphate against water 

 of known oxygen content, say distilled water shaken with air until saturated, 

 taking the temperature and referring to Roscoe and Lunt's table (Sutton's 

 Volumetric Analysis, page 2G0) for the amount of dissolved oxygen present." 



The results obtained compared well with those given by the AYiukler method. 



The detection of extracted paprika, G. Heuser and C. IIassleb {Ztschr. 

 Unlcr.'oicJi. Nahr. u. acHUssnitL, 27 {1914), No. 1-3, pp. 201-209).— For deter- 

 mining whether paprika has been extracted the iodin number is considered 

 satisfactory on account of the ease and rapidity with which it can be deter- 

 mined. The ether extract is, however, a better constant for judging paprika 

 than the alcohol extract. For simplifying and shortening the time necessary 

 for extraction a modification of the Rose-Gottlieb method is suggested. 



A field test for lime-sulphur dipping baths, K. ^Nf. Chapin {U. 8. Dcpt. 

 Agr. Bui. 163 {1915), pp. 7, fig. 1). — The object of this paper is to describe a 

 portable testing outfit devised and employed by the Bureau of Animal Industry 

 for determining the strength of lime-sulphur dipping baths used in the official 

 dipping under regulations now in force. " This method, however, is intended 

 only for field use; It can not replace in the laboratory the more accurate 

 methods of analysis approved by the Association of Official Agricultural Chem- 

 ists. . . . 



" The test here described employs the well-known reaction between soluble 

 sulphids and iodin in neutral solution, whereby sulphur is precipitated and 

 a metallic iodid is formed. It therefore directly estimates, not sulphur, but the 



