355 



three on eacli sort of tobacco. When jmre cnltnres of the bacteria 

 peculiar to any sinjile sort of tobacco were used i'ov iiioculatino- tobacco 

 of anotlicr sort, they induced tlie same taste and aroma as tliey liad in 

 the tobacco from which they were derived. Positive results were 

 secured in every such trial. 



The author therefore believes that the process of fermentation is 

 one of nuich greater importance in improving- the quality of tobacco 

 than has previously been conceded. Up to the present time the imi)rove- 

 ment of the quality has been sought particularly in the nnprovement 

 of the method of culture, and in the introduction of the choicest varie- 

 ties; but this has been only partially successful since the forms of bac- 

 teria inducing the most advantageous fermentation, were not imported 

 with the seed. His results all go to show that tobacco of poorer qual- 

 it\- may be very greatly improved in quality by inoculating with forms 

 of bacteria common to the choicer sorts; and he claims that he has 

 r('peatc<lly so changed the quality of domestic tobacco by regulating 

 tlic fermentation that competent judges were unable to recognize it. 

 Further comnninications are j^romised as to the forms of bacteria. 



Itegardiug the products which the separate forms of bacteria build, 

 definite conclusions are not yet reached; but the author is inclined to 

 believe that among other things a change of nicotine to nicotine-cami)hor 

 takes place duiing the fermentation. 



At what degree of acidity does cows' milk curdle on heating? 

 W. T. Thorner {VJmn. Ztrj., 15 (1801), p. 1108).— The method cnq)loyed 

 for determining the acidity of nulk was as folloAvs: Ten c. c. of the 

 milk to be tested were diluted with 20 c. c. of water, a few drops of 

 phenolphthalein added, and the solution titrated with deci normal 

 potasli solution. The number of tenths of a c. c. of alkali required for 

 neutralization was taken as the degree of acidity of the milk, each 

 tenthofac. c. representing one (emj)irical) degree. As indicated by 

 this method, the degree of acidity of the market milk of the city ot 

 Osnaburg was found to range as follows: At time of imrchase (.'i to 4 

 hours after milking) 120-1G°, hours later, 14°-2.'jO, 24 hours later 

 17o_(;oo^ and 48 hours after this 30O-100o. The more rapidly the milk 

 was cooled after the milking and the cooler it Avas kept, the more slowly 

 did the acidity develop, and the reverse (except where ke])t at a tem- 

 perature above blood heat). In these tests sunlight and darkness seemed 

 t(> have very little eft'ect on the rapidity of souring. 



To determine the degree of acidity at which milk would be coagu- 

 lated l)y lieating to boiling, the author made a large nuinl)er of tests of 

 milk kept from 2^ to 28 hours in a cellar in tlie sunlight and in the 

 dark. The results all point»*d to 23° as the lowest degree of acidity at 

 which milk would curdle on heating. Assuming 20° to be the limit of 

 acidity allowed, he suggests that milk could be rrfi)idly and simply 

 tested by adding 2 c. c. of deci-normal alkali, and a few drops of ])henoI- 

 l)hthalein to 10 c. c. of well mixed milk diluted to 30 c. c. with water. 



