156 



SCIENCE. 



BOOKS RECEIVED. 



The Telescope. By Thomas Nolan, B. S. D. 

 Van Nostrand, 23 Murray Street. New York, 1881. 

 Price 50 cents. 



This little handbook presents very briefly the princi- 

 ples involved in the construction of refracting and re- 

 flecting telescopes, illustrated with about thirty diagrams. 

 For an amateur desirous of following Herschel's example 

 of making his own telescope, this work will be found a 

 practical guide. We notice the author gives the form of 

 object glass suggestod by Messrs. Alvan Clark & Sons, 

 the noted makers of astronomical object glasses. They 

 say "many forms may be used, but from our experience, 

 we have found that to make the crown glass lens of equal 

 curvature, and the flint glass lens nearly flat on the side 

 next the eye, is the most convenient, and gives as good 

 results as any other form. 



MICROSCOPES. 



The American Journal of Microscopy for March is an 

 excellent number full of interesting matter and two full 

 pages of illustrations. 



We notice Professor Phinn corrects a statement men- 

 tioned in Journal of R. M. S. that- 80,000 to 100,000 di- 

 ameter were within the power of his appliances. He now 

 gives as the limit of amplification of a high angle objec- 

 tion, say, an object of one tenth, and a one eight eye- 

 piece, 8,000 to 10,000 diameters. We notice in another 

 part of the Journal that Professor J. Edwards Smith 

 obtains 8,000 with the same-eye piece and a ]/& object. 



Dr. E. Cutler describes a flagellate infusorium called 

 Asthmatos Ciliaris, which occurs in connection with one 

 form of contageous cold coryza or influenza. These par- 

 asites may be easily detected in the early sneezing stage, 

 the nose runs and the eyes water ; they are located in the 

 anterior nasal passages, on the mucus membrane of 

 the conjunctiva of the eyes, and of the pharynx and 

 larynx. Simply transfer a drop of the thin mucus to a 

 slide, cover, then examine with a good 1 -5th and 1 inch 

 occular. 



There appears to be confusion as to the classification 

 of this parasite, and as the opportunity for studying it 

 will probably be oftener than agreeable, we shall be glad 

 to hear from any of our readers who throw light on the 

 subject. 



Dr. F. L. Bardeen considers that wax cells have been 

 too hastily abandoned by their originator, Professor H. 

 L. Smith, who fully described them in " Science." Dr. 

 Bardeen says that if prepared as he suggests, they are 

 the best cells for opaque mounting. 



Dr. A. C. Stokes has an excellent paper on " Growing 

 Slides," and treats the subject in a most exhaustive man- 

 ner ; as most of the contrivances can be made by the mi- 

 croscopist, this article will be of the greatest benefit to 

 this class, 



Dr. Smith Baker, in a paper on.the " Microscopal uses 

 of the Cat," offers a plea tor the more, universal use of 

 this domestic animal in microscopical study. 



In view of the advice offered by Professor Burt G. 

 Wilder, in regard to the use of the cat by anatomists, and 

 the increasing disposition of students to use the cat for 

 such purposes, we fear that this genus will soon be at a 

 premium. 



Manurial Experiment with - Sugar Bekts. — Phos- 

 phoric acid, applied preferably in the spring, increased the 

 yield of sugar most decidedly. — M. Marcker. 



Occurrence of Vanilla in Raw Sugars.— The authors 

 have succeeded in isolating small quantities of vanillinc 

 from crude-sugar.— E. v. LiPPMAN and Prof. C. Sciieibler. 



THE GLYCERINE BAROMETER. 



Mr. James B. Gordon has published the following de- 

 scription of his glycerine barometer — "which appears to 

 have at least one advantage in being easily read off, as the 

 usual tenth of an inch on the mercurial barometer is rep- 

 resented in the glycerine barometer by something more 

 than an inch ; thus the changes which take place are ren- 

 dered obvious even to an unpracticed eye. 



Our readers may have heard of Daniell's water barom- 

 eter, which was destoyed in the fire at the Crystal Palace in 

 1866. Mr. Jordan constructed another, which has since 

 continued in operation. In the course of his experiments 

 on various fluids, he was led to try glycerine, which appears 

 well adapted for the purpose. Its vapor has a very low 

 tension at ordinary temperatures, and as its freezing-point 

 is much below zero, it is, so far, excellently adapted for use 

 in barometers. The mean coefficient of expansion by heat 

 is, according to Professor Reinold, .000303 for a degree of 

 Fahrenheit's scale, and a table has been computed on this 

 basis for reducing the observations to 32° Fahr. Glycerine 

 possessing the capability of absorbing moisture from the 

 atmosphere, its surface in the cistern is covered by a layer 

 of mineral oil, which has no effect whatever on the glycerine, 

 and which does not evaporate at ordinary temperatures. At 

 sea-level the pressure of the atmosphere supports a column 

 of glycerine of a mean height of 27 ft., and accordingly 

 the tube of the barometer is made some 29 ft. in length. It 

 is formed of composition gas-pipe, Hths of an inch in di- 

 ameter, but the upper part, 4ft. or so in length, is of glass 

 tube, having an internal diameter of iin. The top end, in- 

 stead of being sealed, is spread out into a cup-shape, having 

 a small orifice plugged with a stopper of rubber. The cis- 

 tern is of tinned copper 4m. deep and ioin. in diameter, 

 and the air is allowed to press on the surface through a 

 small hole leading into a chamber containing a filter of 

 cotton wool. At the bottom of the cistern is a closed 

 channel opening into the centre, and to this is attached a 

 projecting vertical tube, to which the main tube is soldered. 

 The object of this channel is apparently to provide a means 

 of closing the tube by a screw-plug when refilling is neces- 

 sary. The quantity of glycerine required for such an in- 

 strument is about a gallon, and this being warmed in a 

 water-bath and tinted with rosaniline, sufficient is poured 

 into the cistern to cover the orifice of the channel. The 

 plug at the top end is then removed, and the tube com- 

 pletely filled by pouring the glycerine gently down one 

 side. After allowing it to rest for some time, the air bub- 

 bles will be found collected at the top, when the tube is 

 again filled up to the cup, and the stopper replaced. The 

 screw-plug in the cistern being removed, the column will 

 fall until balanced by the pressure of the atmosphere, and 

 the vacuum is as perfect as it is possible to get it, the small 

 quantity of glycerine remaining in the cup above the 

 stopper hermetically sealing it. The glycerine barometer 

 is therefore a simple and easily managed instrument ; but 

 it is not pretended that it can take the place of the stan- 

 dard mercurial instrument for precision. It is compara- 

 tively a new instrument, and its value as a piece of scien- 

 tific apparatus has yet to be shown. 



Hydroisromic Acid as a Reagent for Copper. — A drop 

 of the solution in question is placed in a watch-glass, a 

 drop of hydrobromic acid is added and the mixture evap- 

 orated at a gentle heat. When it is reduced to the bulk of 

 one drop a rose-red coloration appears, three or four times 

 ! more intense than that produced bv potassium ferrocyanide. 

 In this manner i-iooth milligrm. copper may be detected. 



Detection of Methylic Alcohol in Vinic Alcohol. — 

 MM. Cazeneuve and Cotton propose as reagent a solution 

 of potassium permanganate containing i-ioth per cent of 

 the dry salt. The permanganate at ordinary temperatures 

 is reduced slowly by vinic alcohol, but instantaneously 

 by methylic alcohol. If to 10 c.c. of alcohol at 20° there 

 is added 1 c.c. of the permanganate solution, twenty 

 minutes are required before the liquid takes the 

 yellow tint indicating complete reduction. If 10 c.c. of al- 

 cohol are used containing 1 c.c. of methylic alcohol the 

 yellow tint is instantly obtained with potassium perman- 

 ganate. 



