HARDWICKE'S SCIENCE-GOSSIP. 



i37 



of the lakes in the other parks would also be found 

 prolific, especially in the warm clays of summer. — 

 J. M. Off'ord. 



Preparation of Crystals for the Polari- 

 scope. — The following way has lately been dis- 

 covered by which crystals may be mounted in their 

 own mother liquor. Paint on a slide a thin ring of 

 gold size, whose entire diameter shall equal that of 

 the cover glass, and smooth the edges. As soon as 

 the ring is finished, heat it over the flame of a lamp 

 until it becomes brown. Then make a solution of 

 some substance adapted for polariscope examination, 

 such as salicine, tartaric acid, &c, of such strength 

 that crystals will form only when quite cold. Coat 

 the ring, already hardened, with a little fresh size, 

 and likewise the edge of the cover-glass. Put the 

 slide and cover-glass thus prepared on the hot- 

 plate for a few minutes, and then pour a few drops 

 of the solution into the cell, and apply the cover- 

 glass ; immediately pressing it down gently with a 

 dry cloth, which will absorb the superfluous liquid. 

 Touch the edge of the cover-glass with gold size, and 

 then transfer to the turn-table and finish. The 

 crystals may be seen forming with the polariscope. 

 After standing some time, the crystals lose their 

 sharpness. They, however, can be restored by a 

 fresh application of heat sufficient to cause them to 

 dissolve and recrystallise. The quantity and strength 

 of the solution will modify the results obtained. 



American Exchanges. — Enclosed please find 

 one of the postal cards which I am circulating over 

 our country, and which meet with very good recep- 

 tion by all. Cannot some arrangement be made with 

 English microscopists by which the benefits we derive 

 at home, may be reaped abroad ? Some one at 

 London could act as general collector for the United 

 Kingdom, and transmit to me slides intended for 

 exchange with Americans, and I would return the 

 package with some of our slides. That such a course 

 would be satisfactory to your fellow countrymen, I 

 feel assured by the number of names in the exchange 

 list of Science-Gossip. If deemed desirable or 

 advisable please notice in your next issue, and also 

 write me what you think will be the feeling of the 

 English microscopists. I am corresponding with the 

 micro-men of other countries, and hope that the pro- 

 ject will be as well received abroad as at home. If 

 you need any London reference, I can refer to B. F. 

 Stevens, Esq., 4" Trafalgar Square. — Herman Poole, 

 Microscopic Exchange Bureau, 23 West Swan Street, 

 Buffalo, N. Y. 



The Journal of the Royal Microscopical 

 Society, for April last, contains the full address of 

 the president, Dr. Beale, F.R.S., delivered in Feb 

 ruary last, in which we have the nature and changes 

 in living matter and dead matter, the properties of 

 protoplasm, Bathybius, hidden molecular structures, 

 the "cell soul," &c, severally passed in review. A 



capitally illustrated and fully written paper is that by 

 Mr. A. D. Michael, F.L.S., entitled "A further 

 Contribution to the Knowledge of British Oribatidse," 

 in which the author was assisted by Mr. C. F. 

 George, M.R.C.S. Mr. J. W. Groves has a short 

 paper " On a means of obviating the Reflection from 

 the inside of the Body-tubes of Microscopes ; with 

 suggestions for standard gauges for the same and for 

 sub-stage fittings," &c. There is likewise a short 

 paper by Mr. A. Nachet, "On a Petrographical 

 Microscope." Perhaps the most important part of 

 the " Journal " is the full and ably condensed 

 record of current researches relating to Invertebrata, 

 Cryptogamia, Microscopy, &c. This part is very 

 abundantly illustrated, and by its means the student 

 is kept well posted in all that relates to micro- 

 scopical research all over the world. 



On the Use of Carbolic Acid in mounting 

 Objects for the Microscope. — Some years ago 

 I mentioned in Science-Gossip the use of carbolic 

 acid in mounting microscopic objects, and I am led 

 to believe that the subject is comparatively unknown in 

 England, though in use here more than ten years, and 

 to such an extent that turpentine is seldom used in 

 many studios. The first specimen I saw it tried upon 

 was the head and jaws of a spider mounted by Mr. 

 Ralph, the president of the Microscopic Society of 

 Victoria, which led me to try it in various ways to 

 render objects transparent, and now I seldom use 

 anything else. When I mention carbolic acid, I 

 mean the best crystallised, which can be bought at 

 any chemist's, who will, on being asked, add just 

 sufficient water to keep it fluid. I do not recommend 

 Calvert's so much as many other makers, as it always 

 seems so much more liable to change colour, turn 

 dark, and will then stain many specimens. Whether 

 it is animal or vegetable tissue the effect will be the 

 same, the acid will in a very short time render the 

 object transparent, and the Canada balsam will, when 

 applied, run into the article as readily after it as after 

 turpentine. For experiment let the reader take a 

 mollusc and remove the palate. Wash it well in 

 water, then remove it to a bottle of the acid to stay 

 a few hours, if he is not in a hurry to mount it. But 

 suppose we desire to mount it at once, place it after 

 washing on a glass slip in proper position for mount- 

 ing and drop one or two drops of the acid on it. 

 At first it will look thick and cloudy ; warm the slide 

 over the spirit-lamp, let it cool, and drain off the acid ; 

 if not perfectly clear when cold, apply some fresh acid 

 and warm again ; place on a cover if not previously 

 done, and apply the balsam, by means of a little heat 

 it will run under and the operator will have a slide 

 which will repay him for his trouble. With polyzoa, 

 I find the easiest plan is to place them in a little hot 

 water which softens them, then lay them out on a glass 

 slip ; place another on it which is of quite sufficient 

 weight to keep them in position while they dry, then 



