1018] FIELD CROPS. 139 



Tobacco fermentation experiments, O. de Vrtes {Proefstat. Vorstenland. 

 Tabak [Dutch East Indies], Meded. 21 {1915), pp. 42, pi. i).— This reports ex- 

 periments with piles of fermenting tobacco to determine (1) the absorption of 

 air by the piles, (2) the heat insulation of the piles, (3) heat distribution in 

 the piles, and (4) the overheating of tobacco in piles. The report covers the 

 period of 1910 to 1915 and consists somevi^hat of a compilation of the results 

 of other investigators supplemented by the author's o\/n work. No definite 

 conclusions are drawn, although rather comparable results were obtained. 



An ingenious device is described and illustrated for measuring heat insu- 

 lation. 



Tobacco fermentation tests, N. H. Cohen and H. Jensen {Proefstat. Vorsten- 

 land. Tabak. [Dutch East Indies], Meded. 12 {1912), pp. 38, fig. i).— Studies of 

 the phenomenon of tobacco fermentation are reported in an effort to determine 

 the r61e of bacteria and enzyms and the chemical changes occurring in the 

 process. 



Fermentation was produced at a temperature of 60° C. (140* F.) with a 

 relative humidity of from 80 to 90 per cent. The process is reported as being 

 in no sense bacteriological. Unsatisfactory moisture conditions occasioned a 

 reddish tinge in the tobacco. Together with humidity, temperature exerts an 

 influence on color, high humidity and high temperature resulting in darker 

 color. Mechanical pressure alone had probably no material influence upon 

 color, although a higher percentage of light-colored leaves was observed in the 

 smaller piles. Whether this was due to better ventilation or to decreased 

 pressure was not clear. 



Similar results are reported by Jensen in experiments conducted by him inde- 

 pendent of those described above. 



Observations on the combustion of tobacco, N. H. Cohen {Proefstat. Vor- 

 stenland. Tabak [Dutch East Indies], Meded. S {1913), pp. 29, fig. i).— This 

 paper is presented in three parts, as follows: (1) Methods for determining 

 combustion of tobacco, (2) the influence of the degree of maturity upon com- 

 bustion, and (3) the influence of the potash content upon combustion. 



For the purpose of comparing strains of tobacco, the author recommends the 



use of the formula: Br.=i— p, when Br. la the coefficient of combustion, G the weight 



of the ash, g the initial weight of the sample, and t the time of combustion. Con- 

 siderable tabulated data are presented and discussed in illustrating the use of the 

 formula. 



Samples representative of four degrees of maturity, (1) unripe, without any 

 indication of maturity, (2) ripe, but with yellow tinge, (3) fully matured, and 

 (4) overripe, were analyzed. The conclusion is reached that tobacco should be 

 entirely ripe before harvesting. 



After briefly reviewing the results of other investigators the author con- 

 cludes that it is still an open question as to whether a sufficient weight of 

 potash could be supplied by any practical system of fertilization to improve 

 combustion materially. 



Observations on the combustion of tobacco, O. de Vbies {Proefstat. Vorsten- 

 land. Tabak [Dutch East Indies], Meded. 22 {1916), pp. 5-23, pi. 1; abs. in In- 

 ternat. Inst. Agr. [Rome], Internat. Rev. Set. and Pract. Agr., 7 {1916), No. 8, 

 p. 1119). — The author briefly reviews the observations of Tymstra, Cohen, and 

 others on the combustibility of tobacco and defines the phenomenon as the time 

 occupied in the combustion of a leaf of tobacco stretched horizontally and ignited 

 near its central part. Observations are also reported and illustrated on the 

 color of the ash of small " cigars " made from tobacco of the same origin and 

 40111°— 18— No. 2 4 



