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HARDWICKE'S SCIENCE-GOSSIP. 



as it is always ready for use. Towards the end of 

 his article, I see that Mr. Williams justly laments the 

 time that damar takes to properly fix and dry ; 

 indeed, I have often asked myself the question, 

 " Does it ever get thoroughly dry? " I having found 

 slides quite loose, and the damar sticky, three weeks 

 after mounting. A few weeks since, however, I dis- 

 covered a process by which an object can be mounted 

 in damar, finished with "black japan "or other var- 

 nish, labelled and put in its place in the microscopical 

 cabinet in less than half an hour. The apparatus 

 required consists of a small copper plate, fixed at a 

 convenient height on iron feet ; a spirit-lamp ; a few 

 needles ; and some bullets : conical pistol-bullets are 

 the best. The way I mount is as follows : Having 

 fixed my metal table a sufficient height above the 

 flame of the spirit-lamp (say about two inches), I 

 place my slide on the copper plate, with the object 

 put in the right position for mounting, and the glass 

 eover on top ; this I let warm for about two or three 

 minutes ; then (having previously warmed the tube 

 of damar, which has the effect of making it much 

 more fluid) I drop a small quantity on the slide, in 

 such a manner that the edge of the medium shall 

 come in slight contact with the glass cover : capillary 

 attraction causes the damar (which is now very liquid) 

 to gradually flow under the cover ; if air-bubbles 

 appear around the object, they must be removed by 

 slight pressure and the aid of a heated needle. If 

 the object is not flat, and raises the cover, a bullet 

 placed on the top will keep it down. The above 

 operation ought to take from ten to twelve minutes. 

 Having proceeded thus far, I remove the spirit-lamp 

 from under my table, and let the slide gradually cool. 

 When cold, the damar is quite hard, and the cover 

 firmly cemented. I now (with an old pocket-knife) 

 remove the superfluous damar, wash the slide with a 

 camel-hair brush dipped in turpentine, and then 

 again with the same sort of brush, only using soap 

 and water. Having thoroughly wiped dry the slide, 

 I finish with a ring of "black japan varnish," al- 

 though I believe asphalte will do quite as well, and 

 finally I label and put away in my cabinet ; the 

 whole having been completed in less than half an 

 hour. Of course, " practice alone makes perfect," 

 and the microscopist must expect some few failures 

 to commence -n-ith. The failures most likely would 

 occur from one of the following causes : Too girat 

 heat, thereby making the damar boil under the cover, 

 which would have the effect of destroying the object, 

 — the only remedy would be to at once remove or 

 lower the flame of the lamp. Too liit/c heat, the 

 result of which would be that the damar would not 

 harden when cold. And air-bubbles : these are only 

 got rid of by watching and carefully pressing the 

 cover ; and if that will not remove them, by very 

 gently lifting the cover so as not to distuib the object, 

 and introducing a drop more damar irom the tube, 

 which will no doubt prove effectual. Of the two 



former causes of failure experience alone can pro- 

 perly set right, so as to enable the operator to judge 

 the exact time to keep the slide heated : this any 

 one can easily do after half a dozen attempts. I 

 should be glad if Mr. Williams, or some other gentle- 

 man, would (if they have not already done so) try 

 this mode of mounting, and let me know the result, 

 I feel positive that most of our amateur microscopists 

 would use damar as a mounting medium, especially 

 with the afore-mentioned process, if they only knew 

 how easy it was to work, and what capital results 

 were obtainable. — E. B. L. Bray ley. 



Cleaning Diatoms with Glycerine. — The 

 American N^atiiralist for February gives an account 

 of a process for cleaning diatoms with glycerine, dis- 

 covered by Mr. James Neil. It states that this is an 

 easy and effective way of separating the valves from 

 the foreign matter with which they are usually mixed. 

 Mr. Neil filled a two-ounce graduated measuring- 

 glass three-quarters full of glycerine and water mixed 

 in equal parts. The diatoms, after being heated 

 with acid and thoroughly washed, are then shaken 

 up in some pure water, and poured gently over the 

 diluted glycerine. If carefully done the water and 

 diatoms do not at first sink into the glycerine, but 

 gradually the diatoms sink through the water and 

 into the glycerine, preceding the light flocculent 

 matter held in the water. In a few minutes a pipe 

 introduced closed through the water and into the 

 glycerine will bring up remarkably clean diatoms, 

 which must afterwards be freed from glycerine by 

 repeated washing and decanting. 



The Microscopical Society of Bath. — We 

 have received a copy of the annual address given to 

 the members of this Society by the President, Mr. J. 

 W. Morris, F.L.S., on February 6th. It is a 

 capital discourse on most of the prominent and 

 important topics with which microscopists have to 

 deal, and we think the Society have done right to 

 publish it. 



"Errors of Interpretation," &c. — By an 

 error the figures illustrating Dr. Jabez Hogg's paper 

 on the above subject, in last month's number, were 

 transposed. Fig. 46 represents the "Scales of 

 Diurnal Lepidoptera," magnified 250 diameters ; 

 Fig. 47, the "Scale of a Gnat," magnified 650 

 diameters. 



The Quekett Microscopical Club. —The 

 I thirty-third number of the journal of this well-known 

 ' club has just been published. It contains papers on 

 a new Anti-vibration Turn-tray, by Mr. W. K. 

 I Bridgman ; on a new Universal Reflecting Illumi- 

 nator, by the same microscopist ; and a capital paper 

 by Mr. H. Crouch, on Microscopy in the United 

 States. In addition to the above are papers by 

 Messrs. T. C. White, W. H. Gilburt, G. F. George, 

 , &c. 



