1881.J 



MICKOSCOPICAL JOUKNAL. 



93 



dollar go as far as possible in the 

 purchase, of accessory apparatus for 

 their microscopes, to the fact that if 

 one of the right-angled prisms which 

 are used around chandeliers be held 

 horizontally over the eye-piece, with 

 the widest face from the observer, 

 and the image viewed through it, that, 

 after the two refractions and one re- 

 flection, the image will appear in its 

 normal position ; and that if the 

 prism be held in exactly the right 

 position, the definition will be but 

 slightly, if at all, impaired. It would 

 not be a very difficult task for any 

 one possessed of a little mechanical 

 ingenuity to break off a short piece 

 of the prism, and arrange a support 

 for it over the eye-piece, removing, if 

 necessary, the cap. This device would 

 be of great service to those desiring 

 to dissect or to manipulate material 

 under the compound microscope, 

 and would obviate the necessity of 

 spending from four and a half to 

 eight dollars. 



An erection of the image may also 

 be secured by the interposition of an 

 objective at the end of the draw-tube 

 and immediately above the working 

 objective, but at a great sacrifice of 

 definition. W. 



An Excellent Method of Clean- 

 ing Diatoms. 



The application of the bi-sulphate 

 of potassa in cleaning diatoms has 

 already been recommended twice in 

 the columns of this Journal. I 

 would now offer some additional 

 hints as the result of my experience 

 in its use. It is applicable to the 

 treatment of nearly all varieties of 

 diatomaceous material. Proceed as 

 follows : Crush to powder a few crys- 

 tals of the bi-sulphate of potassa, and 

 add to it a proportionate quantity of 

 the material to be cleaned ; mix in- 

 timately together, and transfer it to a 

 hollow space practiced in the end of 

 a sound piece of charcoal. Then 

 with the blow-pipe direct the flame 

 of a candle upon the mixture, when 

 a violent boiling up will ensue, and 



when it finally ceases to fuse readily, 

 when the potash appears opaque and 

 of a whitish color, it is to be removed 

 and dropped into a thimbleful of 

 water, and boiled a few seconds ; the 

 potash dissolves readily, and liberates 

 the sand and diatoms in a cleaned 

 state. After settling in a shallow 

 porcelain saucer, draw off all the wa- 

 ter and collect the diatoms into the 

 smallest compass possible, and trans- 

 fer them to a nickel ; take the nickel 

 in the wire tongs, and dry with blow- 

 pipe flame ; it will dry immediately, 

 and the diatom powder is to be 

 scraped off and put aside for use. 



All the requisites for the above 

 process consist of a common dime 

 blow-pipe, a small wire tongs six 

 inches long to hold the thimble, 

 nickel, etc., a pocket coin, a brass 

 thimble, a few pieces of sound char- 

 coal, a candle, and a small supply of 

 the Iji-sulphate of potassa. 



When the bi-sulphate cannot be 

 readily procured, an admirable sub- 

 stitute may be found in the follow- 

 ing, viz.: common powdered sulphate 

 of potash, and a small quantity of 

 sulphuric acid, both of which are 

 always found in prescription drug- 

 stores. In using these materials, the 

 diatoms to be cleaned are mixed with 

 an equal quantity of the powdered 

 sulphate of potassa, and a few drops 

 of sulphuric acid are mixed with it ; 

 it solidifies at once, and can be 

 broken into suitable pieces to be 

 fused on the charcoal, as before de- 

 scribed. The superior advantages of 

 the processes here described will be- 

 come apparent to those who have 

 tried the acid methods of cleaning. 

 K. M. Cunningham. 



EDITORIAL. 



— O ! Dr. Marvin, how could you 

 print that very sarcastic squib last 

 month ? Don't you know that our 

 worthy " Brother " has enough to an- 

 swer for already ? Yours was " the 

 most unkindest cut of all." 



