1884.] 



MICEOSCOPICAL JOUENAL. 



149 



lution is now applied, to guard against 

 any defect in the first application. 

 This should run just over the edge of 

 the cover-glass. A careful examina- 

 tion of the cell will show whether 

 the last coat of balsam is perfect or 

 not. It must be continuous around 

 the cover-glass, and if there are any 

 breaks in it they must be remedied. 

 Breaks may occur if the mounting 

 fluid is not entirely washed oft' from 

 the outside of the cell. This is es- 

 pecially the case v^^hen glycerin is 

 used. A good way to do the w^ash- 

 ing is by holding the slide under a tap 

 of running water and using a soft 

 brush. A convenient method is to 

 use a chemist's wash-bottle to direct 

 a stream of water upon the slide. 

 This is the method employed by the 

 writer in preference to any other. 



The only modification of the pro- 

 cess, as thus far described, that can 

 be sanctioned by experience, is the 

 substitution of thin shellac for the 

 balsam to cement the cover down. 

 Shellac may be used for this purpose, 

 and it sei'ves just as well — possibly it 

 is even better when glycerin is the 

 mounting fluid. The operations are 

 precisely the same as when balsam is 

 used. 



5. The fluid is now perfectly well 

 secured, so long as the slide is not 

 handled carelessly. The mounting 

 is, in fact, done, so far as the mere 

 preservation of the specimen is con- 

 cerned. The slides may be kept for 

 years in the cabinet without further 

 treatment. However, the cement 

 holding the covers is very thin, and 

 as balsam becomes brittle after awhile 

 the covers would be likely to come oft' 

 by rough usage. They should, there- 

 fore, be secured by a protective ce- 

 ment, and it is our custom to set 

 them aside in the condition just de- 

 scribed until a number have been 

 prepared, when they are all rapidly 

 carried through the finishing process 

 together. 



The protective cement in most fa- 

 vor with us is the mixture of equal 

 parts of asphalt or Brunswick black 



and gold size. This is applied in 

 two or three coats, each being al- 

 lowed to dry separately, until the 

 cover is well secured. 



6. The final operation is the finish- 

 ing, which is merely the application 

 of a coating of asphalt or Brunswick 

 black alone, to give a fine black polish 

 to the cell. ^ 



Having given this method of mount- 

 ing in detail, we repeat that if the in- 

 structions are carried out the mounts 

 will never fail. We trust that the 

 method will be adopted by many per- 

 sons who have used balsam hitherto, 

 under the impression that ftuid prep- 

 arations could not be relied upon. As 

 thus prepared they are sure to stand, 

 as the experience of years has shown. 



Sand.* 



BY J. G. WALLER. 



A grain of sand is one of the small- 

 est of visible atoms, and as such pass- 

 es into the language of metaphor. 

 The aggregation of sand, as a sj^mbol 

 of untold multitude, is probably fa- 

 miliar to every language upon earth. 

 In the operations of nature, ^vorking 

 about us, we are ever being astonish- 

 ed at the minuteness of an individual 

 agent towards the inighty end. So 

 it is with sand, not only as it is work- 

 ing now, but as it has worked in il- 

 limitable ages past. The attrition of 

 hard particles — silex — whether pro- 

 duced by storm floods, river torrents, 

 or the tempestuous waves of the ocean, 

 plays a part in its production, block- 

 ing up estuaries, and forming at the 

 mouths of rivers dangerous shoals. 

 This is mostly shown by those grand 

 rivers of the earth draining large con- 

 tinents, and not tidal. But at the 

 mouth of our own Thames, which is 

 tidal, and a mere pigmy in compari- 

 son, we have large sandy deposits, 



♦Although this article was published two years ago, 

 our attention has only recently been especially drawn 

 to it through some examinations of sand of our own 

 coasts that have been made of late, but not yet 

 published. The article seems worthy of republication 

 even at this late date. It is from the yourn. Quekett 

 Micr. C/»l>.—Exi. 



