HARDWICKE'S SCIENCE- GOSSIP. 



15 



the covers after they have been cleaned and rendered 

 fit for use. 



The last requirement will be a small india-rubber 

 bottle or ball, with a fine tube or pipe to enable it 

 to be used as a syringe or " bellows," to blow off the 

 dust, &c, which is the final operation in cleaning. 



Being thus provided, we are now ready to com- 

 mence operations, and as the covering glass for dry 

 cells must necessarily be of sufficient thickness to 

 resist some degree of pressure, the covers will be 

 strong enough to bear a fair amount of careful 

 handling, therefore they may be taken up and held 

 by the edge, between the thumb and two or three 

 fiugers, so as to present one of the surfaces upwards. 

 Let this surface, as well as the end of the paper 

 rubber, be strongly breathed upon, and then with 

 gentle friction the glass may be rendered beautifully 

 clean and clear, after which let it have three or four 

 strong puffs from the blower, and be instantiy in- 

 verted upon the wash-leather table, having first 

 blown off any dust which may have gathered upon 

 it. Here it may remain until wanted, when it can 

 be taken up by a three-pointed needle forceps, and 

 dropped on to its place and adjusted for com- 

 pletion. 



Blotting-paper has been found to cause the least 

 degree of excitation in the glass, as well as being 

 very efficient in producing a brilliant surface without 

 injuring it, while any fibres remaining are readily 

 dispersed by the blast of cool air, which is also very 

 effective in destroying any electrical attraction, 

 which may have remained in the cover. Eor clearing 

 the covers of slides during examination these paper 

 rubbers are most serviceable, but in cleaning the 

 lenses of eyepieces, &c, they are unequalled, and 

 when accompanied by the blowing process,the plan is 

 invaluable, especially with the " Kelners," where the 

 slightest particle of dust forms a highly obtrusive 

 blemish, but which can thus be readily avoided. 



W. K. Bridgman. 



Anagallis arvensis. — In Lord Bacon's 

 works I find it written, "There is a small red 

 flower in the stubble fields, which country-people 

 call the wincopipe, which, if it open in the 

 morning, you may be sure of a fair day to 

 follow." This description seems to refer to 

 Anagallis arvensis. Is that flower known by 

 such a name now in any part of the country ? It 

 is not mentioned by Dr. Prior, but perhaps some of 

 your rural readers may be acquainted with it, and 

 can explain its origin.— F. W. 



The History of the Moon. — " The moon 

 exhibits in high relief an advanced stage of the 

 fiery history of our earth. There the process of 

 cooling has gone so far that even volcanic action 

 has ceased."— Ennis's Origin of the Stars. 



MICROSCOPY. 



An Ingenious Turntable.— At the annual 

 soiree of the Oldham Microscopical Society, recently 

 held, there was an exceedingly large and creditable 

 array of objects. A noticeable feature in the exhi- 

 bition was a new and most ingenious form of turn" 

 table, made by Mr. Charles Butterworth, of Shaw, 

 by the aid of which cement cells, so invaluable in 

 microscopic mounting, could be made with the ut- 

 most precision and despatch, and that too not only 

 in the circular but also in the elliptical form, of any 

 size from 2 in. in length to 1 in. in width, reducible 

 until a perfectly straight line was produced ; by its 

 aid also a thin glass cover could be held in position 

 ou a cell so made whilst the finishing ring or rings 

 of cement were added. The invention excited much 

 attention, and was considered by the members as 

 the most complete appliance of the sort yet intro- 

 duced. 



Eitting High-power Object-glasses.— What 

 is the method of fitting a high-power object-glass 

 purchased separately from a microscope, so that it 

 shall be accurately in centre ?— H. W. E. 



Varnish for Microscopic Cells. — Your corre- 

 spondent " W. G. C." asks for a recipe for the 

 white varnish used in ring shells. The following 

 was given to me by a scientific instrument maker. 

 Ingredients: chloroform, gum dammar, white oxide 

 of zinc, and boiled oil, the same as used by colour- 

 men. The gum dammar, is dissolved in chloroform ; 

 just sufficient oil is mixed with the oxide of zinc to 

 make the powder into a coherent mass, the oil and 

 powder being worked together in a mortar. The 

 thick paste so formed is put into the chloroform 

 solution, the mixture being well shaken. Ex- 

 perience alone will instruct the maker in the quan- 

 tities of the ingredients. To make coloured 

 varnishes, instead of oxide of zinc, vermilion, 

 Prussian blue, emerald-green, or even lampblack 

 may be used, according to the colour required.— 

 B. S. T. 



Finishing Varnish.— In reference to"W.G.C.'s" 

 query about a good white or coloured finishing 

 varnish, in December's number of Science-Gossip, 

 he may be glad to know that I tried last year, and, 

 as far as I can see, successfully, the ordinary oil 

 colours in tubes ; they are easily used, and can be 

 thinned with turpentine, or any of the mediums in 

 use amongst artists ; of these, however, I think 

 " drying-oil " is the best, as it dries firmly, and is 

 not apt to become sticky in hot weather. Of course 

 the fast-drying colours are to be preferred, flake- 

 white, vermilion, French ultramarine, emerald- 

 green, all dry well, and dry better if mixed with 

 flake-white. A white varnish consisting of nitrate 



