CHEMISTRY. 11 



fodder analysis an examination should be made for noxious weed seed. 

 The presence of such indicates whether the material has been adulter- 

 ated, as for instance with grain refuse. It is not necessary to determine 

 the number and the kind of weed seed and to calculate their proportion 

 per kilogram. 



(3) If a microscopic examination of the feeding stuff shows an unusual 

 amount of smut spores, this fact should be reported as well as the joos- 

 sible danger from this source. 



The recommendation that feeding stuffs be examined for ergot was 

 referred to the section on feeding stuffs for further investigation. 



A discussion of the food value of the carbohydrates was postponed, 

 at the suggestion of the reporter, until more preliminary work has been 

 done on this subject. 



Determination of the specific gravity of curdled milk, M. Wet- 

 bull {Milch Ztg., 23 (1894), No. 16, pp. 247, 24ti).—\n a previous article^ 

 the author stated as the result of experiments that when a definite 

 volume of ammonia was added to curdled milk the contraction in volume 

 was so slight that the specific gravity of the milk could be calculated 

 witli the formula: 



Vol. of aminouia X sp. gr. of aniiuonia -+- vol. of milk X sp. gr. of milk = vol. of the 



mixture x its sp. gr. 



As the specific gravity of the milk is the oidy unknown factor this 

 is easily calculated. 



The method has since been tested by J. Okulitsch,^ who invariably 

 obtained too low results. The samjjles tested by him were rather high 

 in specific gravity, and he used only 3 per cent ammonia. 



The author then made a second series of experiments with 22 samples, 

 using different amounts of ammonia, which he reports in the present 

 pai)er. The specific gravity was determined with a Westphal balance 

 and with a picnometer, and the mixture was allowed to stand an hour 

 or so after adding the ammonia to allow the air bubbles to rise. The 

 author's conclusions from the experiments are that — 



(1) The specific gravity of normal milk which has stood for 1 or 2 

 weeks and curdled can be accurately determined by the method given. 



(2) With the addition of common ammonia equal to one tenth of the 

 volume of the milk, the error does not exceed 0.0005 in careful work. 



(3) Owing to the contraction the results are more likely to be slightly 

 too high than too low. 



(4) In accurate work it is advisable not to materially exceed the 

 amount of ammonia mentioned, since the error in reading is then mul- 

 tiplied, and the reduction to 15° C. is more dilhcult, as the tables for 

 conversion do not include the figures for such thin milk. 



Determination of fat in cheese, F. H. Werenskiold {Rpt. Chem. 

 Control Sta. Christiania, 1893, pp. 28, 29). — Comparative determina- 



' Chem. ztg., 17 (1893), p. 1670; abs. iu Milch Ztg., 22 (1893), p. 786. 

 « Milch Ztg., 23 (1894), p. 84. 



