1881.] 



MICROSCOPICAL jour:n^al. 



113 



to distinguish one from the other. 

 What may be regarded as the perfect 

 oleomargarine, does not contain crys- 

 tals. The controversy between Mr. 

 J. Michels and Dr. H. A. Mott is still 

 fresh in our memories, and can hardly 

 be regarded as very creditable to 

 either side. I have no doubt that 

 Mr. Michels did see just such things 

 as are depicted in the limes of June 

 27th, 1878 (Fig. 6), and Dr. Mott's 

 very unprofessional criticisms were 

 quite uncalled for. The fact is, as I 

 hope to show you this evening, that 

 some specimens of oleomargarine do 

 contain bundles of distinct crystals, 

 while others do not. As regards the 

 impurities which have been stated to 

 occur in artificial butter, such as 

 muscular tissue and animal matter of 

 various kinds, I have never been able 

 to identify a single shred of muscle 

 in any of my examinations. How- 

 ever, a certain amount of debris, 

 which very likely comes from the fat- 

 cells — the adipose tissue — does occur 

 in the artificial product, but these 

 can hardly be regarded as a distinc- 

 tive characteristic of the product. 

 In the absence of distinct crystals, a 

 person who is familiar with the ap- 

 pearance of both butter and oleomar- 

 garine under the microscope, would 

 probably be able to distinguish one 

 from the other by the general appear- 

 ance of the field, but not from any 

 characteristics that can be definitely 

 described. The artificial product 

 possesses a certain grain, especially 

 when examined v/ith a power of 

 1,000 diameters or more, which is not 

 resolved into a minutely, crystalline 

 structure, but which, nevertheless, 

 shows some indications of a crystal- 

 line arrangement of the particles. 

 Such an appearance is not to be ob- 

 served in butter. 



Ivory Drop-Black. 



The above is a material which I 

 have been using for more than 

 eighteen months as a background for 

 all of my opaque mounts. With the 



exception of a few persons in this 

 city to whom I have communicated 

 my method, I do not know of its hav- 

 ing been used for this purpose ; and 

 it makes, when properly applied, a 

 beautiful, smooth surface. I have 

 tried various kinds of drop black, 

 but now I use only the " XXX ivory 

 drop-black " of Sherwin, Williams & 

 Co., of Cleveland, O. 



This is put up in collapsible tubes, 

 selling ordinarily at twenty-five cents ; 

 I am told that it is ground in japan, 

 and not in oil. It gives the finest 

 ground of any black color I have been 

 able to procure. Drop-black ground in 

 oil will not do, as it always dries with 

 more or less gloss. 



The following is my method of 

 using it. Press a small quantity of 

 the color into a one-ounce, wide- 

 mouth bottle, and thin it sufficiently 

 with fresh turpentine ; it may be 

 made quite thin. 



The slide being on the turn-table, 

 whirl the latter and apply the color 

 with a brush. If the color is too 

 thick, it will be found that it cannot 

 be smoothly spread, and that it will 

 dry in ridges. If too thin it will be 

 found necessary to make several 

 applications. If it is necessary, a 

 second application can be made 

 within fifteen or twenty minutes. 



I generally use curtain rings for 

 my opaque mounts, and these rings 

 are afterwards attached to the slides 

 by means of Brunswick black or 

 marine glue. 



I would advise all who try this 

 process to get the very best color, 

 and to be sure it has not been ground 

 in oil, and also in thinning it to use 

 only fresh turpentine, as the older 

 the turpentine is, the more likely will 

 it be to dry with a greasy appearance. 

 The ring being attached, I freely ap- 

 ply the Brunswick black around the 

 edges inside. This being dry I apply 

 white color on the same edges, 

 which assists in the illumination. 

 When dry the cell is ready for the 

 object. 



Ed. Grahn. 



