Augusts, 1900.] 



SCIENCE. 



191 



hours, and it would be difficult in a large 

 telescope to measure that arc of 10'. We 

 find that with the great telescope at Wash- 

 ington we are limited to 4' or 5'. Beyond 

 that we do not get good results. You can- 

 not make the observations without shifting 

 the eyepiece ; and I have made up my mind 

 that for the purposes of micrometric obser- 

 vation the diurnal plan would be out of the 

 question. 



J, G. Hagen. Eeferriiig to the photo- 

 graphic method, there is a difficulty which 

 has not been discussed. The motion of the 

 planet, in taking a photograph, which may 

 require an hour or more, will produce a 

 trail. There is an opportunity to choose 

 between allowing the planet to trail, and 

 allowing the stars to trail. Perhaps the 

 same object, of securing an accurate posi- 

 tion for the planet upon the plate, can be 

 attained by interruption of the exposure. 

 The time of the motion can be known 

 within ten seconds ; and while the planet, 

 of the 9th magnitude, may be obtained 

 upon the plate, the bright stars may be 

 obtained in a series of dots, each expos- 

 m-e giving an independent determination. 

 Whether these interruptions should be 

 made once in ten seconds or once in a min- 

 ute is a question for experiment. I merely 

 make the suggestion of a method that may 

 remove the difficulty. 



Adjourned. 



Geo. C. Comstock, 



Secretary. 



Washburn Observatory. 



SCIENTIFIC BOOKS. 

 Curing and Fermentation of Cigar Leaf Tobacco. 

 By Oscar Loew. Report No. 59, U. S. De- 

 partment of Agriculture. 1899. Pp. 34. 

 Physiological Studies of Connecticut Leaf To- 

 bacco. By Oscar Loew. Report No. 65, 

 U. S. Department of Agriculture. 1900. Pp. 

 57. 



The great and growing importance of the to- 

 bacco industry in the United States has led the 



Department of Agriculture to undertake an ex- 

 tensive series of investigations, covering the 

 mapping of areas of soil suitable for raising to- 

 bacco, studies in fermentation, improvements in 

 breeding and selection, the conditions of growth 

 and manipulation in foreign countries and the 

 question of supplying tobacco to foreign mar- 

 kets. Dr. Loew has been detailed to carry out 

 the chemical part of these researches, and the 

 above-mentioned documents set forth the re- 

 sults thus far obtained by him and by others, 

 and contain an abundance of material, both of 

 scientific interest and practical importance. 



From the consumer's standpoint essential 

 constituents of tobacco are : (1) nicotine ; (2) 

 certain compounds, the chemical nature of 

 which is wholly unknown, which impart to the 

 leaf its acceptable flavor or aroma, and which 

 differ in quality and quantity in different grades 

 of tobacco. It is upon the latter, rather than 

 upon the nicotine, that the commercial value 

 of the prepared leaf mainly depends. The 

 amount of nicotine is largest in the fresh leaf 

 and undergoes marked diminution during fer- 

 mentation, while the aromata are developed 

 during the processes to which the tobacco is sub- 

 jected. There is no apparent relation between 

 the color, aroma and amount of nicotine. 



The preparation of tobacco comprises two 

 stages, curing and fermentation or 'sweating,' 

 sometimes supplemented by aging or ' cold 

 sweating. ' During the earlier part of the cur- 

 ing stage the cells are still alive, and the result- 

 ing changes are physiological, embracing among 

 others the transformation of starch into sugar, 

 and the partial respiratory consumption of the 

 latter, or its transference to another part of the 

 leaf and reconversion into starch. After the 

 death of the cells, the proteolytic and oxidizing 

 enzymes attack much of the protein, fat and 

 tannin, and give rise to changes of color and 

 flavor. The curing stage is followed by one of 

 fermentation, which goes on under the influence 

 of air and moisture, and which is accompanied 

 by a marked rise of temperature. During this 

 stage there is a notable decrease of nicotine, 

 but an improvement of flavor and aroma. The 

 fermentation was ascribed by Suchsland to the 

 action of bacteria, and he attempted to impart 

 to German tobacco the peculiar Havana flavor 



