1894 THE MICROSCOPE. 173 



butterfly scales, etc., etc., many a slide has been ruined and 

 much patient labor wasted by attempting to cement the object 

 to the slides with common mucilage. The following recipe will 

 aff'ord better and more satisfactor}'' results. 



Selected pieces of gum Arabic are dissolved in distilled water 

 so as to form a thin mucilage. This is filtered, and the filtrate 

 poured into a considerable volume of alcohol, which precipitates 

 the arabin. This is separated from the mother liquor by filtra- 

 tion washed with alcohol and finally dried. 



For ase, dissolve a small portion in water and apply a thin 

 film to the slide with a camel's hair brush. As each diatom or 

 object is mounted, gently breath upon it and the moisture will 

 fasten it to the slide. 



Crystal slides. — Make a cold saturated solution of a salt ; 

 then heat the solution so that it will dissolve still more of the 

 salt. A cell is then filled wdth the warm solution, and imme- 

 diately sealed. Upon cooling, the crystals will be deposited 

 within the cell in a most beautiful manner, and their lustre will 

 be retained. Gold size is a suitable cement for slides prepared 

 in this manner. 



SCIENC^^OSSIP. 



A Comple Set. — One of the very few men who have com- 

 plete sets of The Microscope and Microscopical Journal from 1881 

 to date, is Dr. E. F. Hodges, of Indianapolis. He also has the 

 Journal of the Royal Microscopical Society complete. These 

 sets are of great value for reference and when sold command a 

 high price. 



Fermentation. — Evening classes for the study of fermentation 

 are to be held by Prof. F. W. Fellowes, 61 Chancey lane, Lon- 

 don. There will be six weekly lectures of especially interest to 

 brew^ers, bakers and analysts, with practical demonstrations. 



Fruit Skins. — The bloom of a peach is a luxuriant growth 

 of microbes. All fruit skins carry germs and so should never 

 be eaten, for the stomach may enable them to multiply inde- 

 finitely especiall}^ in old or feeble persons. 



Microscopical Praxis. — This is the name of Dr. Stokes' new 

 book, just issued. It will be of much assistance to the student. 



