1881.] 



MICROSCOPICAL JOUENAL. 



51 



jective of 40° aperture and half an 

 inch working-distance, giving about 

 forty diameters' magnification with 

 the ordinary No. i ocular, and resolv- 

 ing 38,000 lines to the inch ; 2. An 

 objective of 100" aperture and one- 

 eighth of an inch working-distance, 

 giving about 120 diameters' magnifi- 

 cation, and resolving 70,000 lines to 

 the inch ; 3. A homogeneous immer- 

 sion objective of 120° balsam angle of 

 aperture, giving about 300 diameters' 

 magnification, and resolving 120,000 

 lines to the inch. Proper eye-pieces 

 would make these three objectives 

 cover the intermediate magnifications 

 desirable, and the third objective in 

 the list would resolve any test resolved 

 by any glass yet made and in the 

 market ; whilst the 40° glass would 

 give all the "penetration" needed for 

 the binocular with opaque objects. 



Detection of Starch-glucose in 

 Sugar. 



[ The adulteration of sugars with 

 starch-glucose is extensively prac- 

 ticed, and various methods have been 

 devised to detect the fraud, but none 

 of them are so simple as the one 

 described by Mr. Casamajor in the 

 following letter. — Ed.] 



Last evening, at the Conversazione 

 of the Chemical Society, I showed 

 how easily the adulteration of sugar 

 by starch-glucose, can be detected by 

 the microscope. 



I Tiad two samples of coffee-sugar, 

 one being a pretty high grade sugar, 

 and the other being of as low a grade 

 as there is in the market; I had, 

 besides, a sample of the starch-sugar 

 in small grains, which is used to 

 adulterate sugar, and also a sample 

 of adulterated sugar, " new process 

 sugar," so-called. 



Both the samples of coffee-sugar, 

 when seen by reflected light through 

 an A eye-piece and a ^ objective 

 present a beautiful appearance. Every 

 crystal is perfectly formed and 

 thoroughly transparent. A group of 



these crystals looks like a mass of 

 rock-candy. 



The grains of starch-glucose are 

 opaque and look like pieces of tallow. 



In the adulterated sugar, the crys- 

 talline grains of real sugar and the 

 opaque, amorphous grains of starch- 

 sugar m.ay be seen side by side with 

 great distinctness. 



I send you herewith samples of 

 coffee-sugar, also samples of starch- 

 sugar and of the adulterated sugar, 

 that you may see them for yourself. 

 P. Casamajor. 



Brooklyn, Feb. 22d, 1881. 



The Preparation of Tegetable 

 Sections. 



There are few mounted objects that 

 are more attractive than well-made 

 preparations of vegetable tissues, and 

 there are none more easily prepared. 

 The symmetrical arrangement of the 

 cells as shown in a cross-section of a 

 stem often makes a beautiful object, 

 but even this can be greatly improved 

 by double staining. For the ordinary 

 purposes of the microscopist the cell 

 should be freed from their contents 

 of protoplasm, starch, etc., but for 

 some purposes, as in the study of cell 

 growth, for example, it is necessary to 

 retain these constituents. It is in- 

 tended to describe in this article only 

 the process of preparing the speci- 

 mens with the cell-contents removed. 



Select stems or leaves of a suitable 

 size, and if the former are tough or 

 hard, soak them in water to soften 

 them. Leaves should be placed in 

 alcohol if they are not to be im- 

 mediately cut, but stems of hard wood 

 may be preserved dry; the softer kinds 

 should be placed in alcohol. They 

 may be tied in a small bunch with a 

 piece of thread and a slip of paper 

 with the name written with a pencil 

 attached, and several such bunches 

 may be preserved together in a bottle 

 of alcohol. 



The first operation is to cut the sec- 

 tions, and, as the methods for doing 

 this are well described in the element- 



