220 



CHEMISTRY. 



oxygen, prevents the development of the vine- 

 gar eels ; and the natural aroma of the original 

 liquid is also more fully retained. (Comptes 

 Eendus, July 7, 1862.) 



New Hydrometer. The "Scientific Ameri- 

 can," May 24, 1862, contains a description of a 

 hydrometer, the invention of Mr. Peter Hogg, 

 of Brooklyn, N. Y., and which is designed to 

 indicate densities of liquids equally well at any 

 ordinary temperatures. The comparisons of 

 the densities of different liquids, made with the 

 usual forms of hydrometer, can only be strictly 

 correct when the liquids themselves have the 

 same temperature ; and when, as is frequently 

 the case in the process of refining sugar, and in 

 other manufacturing processes, a portion of the 

 liquid or solution must be cooled to the exact 

 point taken for the standard of density, the 

 operation is one of difficulty and requiring time, 

 the result being that absolutely accurate tests 

 are in this way rarely obtained. The new hy- 

 drometer, intended to obviate these difficulties, 

 consists essentially of a tube closed at its lower 

 end by a flexible diaphragm, and which, while 

 placed in a vessel of water, is filled with the 

 same liquid up to a certain point. When this 

 tube so filled is afterward plunged, up to the 

 same point, in any liquid to be tested, the con- 

 tained water being soon brought to the same 

 temperature as the surrounding liquid, it will 

 follow that, according as the specific gravity of 

 such liquid in contact with the outside of the 

 flexible diaphragm is greater or less than that 

 of the water resting on the inside of the same 

 diaphragm, the column of water in the tube 

 will be thereby caused to rise or fall ; and the 

 tube being properly graduated, the specific 

 gravity of the liquid will be indicated by the 

 height at which the column of water comes to 

 stand within it. As a further part of the in- 

 vention, the hydrometer described is so placed 

 within an inverted syphon, through which the 

 liquid to be tested may flow constantly, that 

 the specific gravity of the liquid can be at any 

 time ascertained, by simply observing at what 

 point of its scale the hydrometer tube stands 

 immersed in it. 



Myrtle Wax. The fruit of the bayberry 

 (Myrica cerifera) yields a wax which, under 

 the names of myrtle wax, candleberry wax, 

 and bayberry tallow, has for some years form- 

 ed to some extent an article of commerce in 

 this country. It occurs abundantly as a white 

 incrustation on the small globular berries of 

 the plant. These berries being inclosed in 

 bags of coarse cloth and kept immersed in boil- 

 ing water, the fused wax collects on the sur- 

 face, and is then poured off into pans to solid- 

 ify: as thus obtained, it is nearly pure, and 

 in this state passes directly into commerce. It 

 is employed as a lubricant for rubbing surfaces 

 of wood, as a polish for furniture, as a substi- 

 tute for beeswax in the manufacture of candles, 

 and in medicine. The commercial wax is of 

 various shades of color, from a grayish-yellow 

 to deep green; more hard and brittle than 



beeswax; sp.gr. 1.004 1.006; point of fusion 

 very constant at 117 120 F. Mr. G. E. 

 Moore, of the Sheffield Scientific School, Yale 

 College, has carefully examined the chemical 

 constitution of the myrtle wax ; and he is led 

 to conclude that Chevreul's analysis, giving as 

 its components glycerine, stearic, margaric, 

 and oleic acids, must have been performed on 

 an adulterated sample of the article. His own 

 conclusion is that the pure wax consists of 

 palmitin, about \ part, the remaining being 

 free palmitic, with a small quantity of lauric, 

 acid the latter either free or in the state of 

 laurin. He accordingly suggests this body as, 

 to chemists, a convenient source of palmitin 

 and palmitic acid ; while, in the arts, its high 

 illuminating power, cheapness, and probable 

 facility of bleaching, recommend it especially 

 as a hardening ingredient in the manufacture 

 of various sorts of candles, including those of 

 paraffine. The abundance and hardy habits of 

 the plant, its thriving upon poor soils unfit for 

 other crops, as near the sea, the slight atten- 

 tion requisite to insure an abundant yield, and 

 the ease of -extraction of the wax itself, com- 

 bine to indicate the preparation of the myrtle 

 wax as a branch of industry which has not yet 

 received the attention it deserves. ("Amer. 

 Jour, of Science," May, 1862.) 



Aniline Colors. A very full article on the 

 celebrated colors derived from aniline, or which 

 in other words are products of coal tar, by Mr. 

 Perkin, the original producer of the aniline 

 purple (mauve), will be found in the "Amer. 

 Jour, of Science," Sept. and Nov. 1861. By a 

 recent series of researches upon the aniline 

 colors, which no one had previously obtained 

 in a state of purity, Prof. Hoffmann has been 

 able to reduce these to two types (rosaniline 

 C 2 o Hi Ns) and levcaniline (C 20 H-u N), which 

 thu,s bear to each other the same relation as 

 do the blue and the white indigo. The subject 

 of the aniline colors is one of too great extent 

 and complexity to bear condensation within a 

 limited space. For the latest information re- 

 specting the composition of these coloring mat- 

 ters, their relation to other products obtained 

 from coal (including the various hydrocar- 

 bons), their production, and use in dyeing, the 

 reader is referred to the article above cited ; to 

 Prof. Hoffmann's recent paper on the subject, 

 in the "Philos. Magaz.," Dec. 1862, Supple- 

 ment; and to a report of a lecture by him be- 

 fore the Royal Institution, copied in the " Sci- 

 entific American," Sept. 20, to Oct. 4, 1862. 



ParTcesine. The basis of this new composi- 

 tion, articles manufactured from which attract- 

 ed some attention in the Exhibition of 1862, is 

 a mixture in certain proportions of castor oil, 

 collodion, and chloride of sulphur. With these 

 may be combined certain resins, gums, or 

 earthy matters, according as a flexible, plastic, 

 or hard and rigid material is desired, and also 

 matters imparting the required colors to the 

 mass. The mixture of the principal ingredients 

 results in a sort of combination, and almost 



