308 



SCIENCE 



[N. S. Vol. XXIX. No. 73S 



Attention is called to the varying emphasis 

 given to the lead test in cider vinegar analysis 

 and the reagents employed. The test is shown to 

 be of particular value in the case of a turbidity 

 only being produced on the addition of neutral 

 lead acetate to the vinegar being examined. The 

 turbidity together with failure of the vinegar to 

 give a copious precipitate is due to the presence 

 of the normally insoluble pectinous constituents 

 of the apple marc due to heating either through 

 fermentation or steaming of second pressings or 

 through the employment of badly fermented and 

 heated apples for the manufacture of the vinegar. 

 Increase in the right-handed polarization and of 

 reducing sugars on inversion gives confirmatory 

 evidence as to the presence of second pressings or 

 employment of badly fermented stock. The neu- 

 tral lead acetate is shown to be more delicate in 

 its reaction than lead subacetate for the lead test, 

 while the addition of alcohol, which is sometimes 

 advocated, is not permissible as alcohol readily 

 precipitates the pectinous bodies causing the tur- 

 bidity, thus destroying the value of the test. 



Normal Occurrence of Borio Acid in Virginia 



Peanuts: F. A. Noeton. 



Reference is made to previous work showing the 

 presence of traces of boric acid in apples, pears, 

 quinces, grapes, pomegranates, peaches, gooseber- 

 ries, cherries, oranges and lemons. Also in hops, 

 radishes, lettuce, carrots and sugar beets, the 

 maximum amount of boric acid normally occur 

 ring which has been reported being .016 per cent, 

 Eeference is then made to work at the National 

 Canners' Laboratory, showing the normal occur 

 rence of boric acid in two lots of Virginia peanuts 

 the amount being .015 per cent. 



To Determine Fat in Sioeetened Condensed Milk 



C. E. Cochran. 



Weigh out 25 grams of the sample, dissolve in 

 water and make up to 100 c.c. Transfer 6 c.e. to 

 a double-tube milk flask provided with a small- 

 bore tube graduated to give percentage of fat for 

 5 c.c. milk. Add 4 c.c. of ether and 4 c.e. acetic 

 acid (80 per cent, or more absolute acetic acid). 

 Acetic acid of this strength will dissolve the curd, 

 but has no effect on the sugar. Place the flask in 

 a vessel of warm water and heat until the ether 

 is expelled. A layer of milk fat will now be seen 

 floating on the surface of a clear and colorless 

 liquid. Fill the flask with hot water, thus raising 

 the fat into the graduated tube. The percentage 

 of fat can now be read, the sample whirled in a 

 centrifugal machine and another reading made. 

 Multiply the reading by four. 



The Anti-putrescent Effects of Copper Salts: 



Alfred Springer. 



The peculiar behavior of the " certified and in- 

 spected milk" from the largest dairy impressed 

 some of the chemists of this city with the belief 

 that some antiseptic had been added to cause this 

 milk to remain sweet. The milk commissioners 

 and owners of the dairy in question indignantly 

 denied that such was the case. After a long series 

 of tests I found small quantities of copper salts 

 present in all the bottles of certified and inspected 

 milk coming from this dairy; furthermore, traced 

 its presence largely to a boiler compound used, 

 containing copper salts, which primed over in the 

 sterilizing room. The milk is especially abnormal 

 in never becoming putrescent, and showing, when 

 exposed to the atmosphere peculiar growths of 

 molds, which are described in the paper. 



Experiments to show the anti-putrescent effects 

 of copper salts with meat, egg and blood albvimin, 

 sewage and other substances are also described. 



The Composition of the Oregon Hop: C. E. 



Bradley. 



A study of typical hop plants with respect to 

 their requirements of the soil gives values for 

 phosphoric acid similar to those reported by Wolff. 

 Nitrogen and potash are, however, less by one half 

 in Oregon samples. Choice fresh hops yield .48 

 per cent, of oil by steam distillation. The resin 

 content of sixteen commercially graded samples is 

 reported, choice grades giving from 12.32 to 13.75 

 per cent, soft resin and from 5.35 to 6.59 per cent, 

 hard resin. 



The Effect of Low Temperatures upon B. coli and 



B. typhosus in Sterilized, Artificially Infected 



Milk: Geo. W. Stiles, Jr. 



This investigation involves a bacteriological 

 study of sterilized market milk artificially in- 

 fected with pure cultures of B. coli and B. ty- 

 phosus. Ninety small Erlenmeyer flasks contain- 

 ing 50 c.c. each of the infected milk were placed 

 at ordinary ice-box (53°-63° F.), chilling (30°- 

 34° F.) and cold-storage ( — 5°-8° F.) tempera- 

 tures. 



At intervals of three to four days one flask 

 from each lot was removed and the number of 

 colonies determined by plating on plain agar, 

 being incubated four days at 25°-27° C. The ini- 

 tial bacterial content having been determined, the 

 change in numbers varying from this standard are 

 represented diagrammatically. 



At ordinary ice-box temperatures the number of 

 organisms, both B. coli and B. typhosus, multiply 



