118 



THE AMERICAN MONTHLY 



[June, 



4. Section of kidney of jack rabbit. 

 Geo. C. Faville. 



5. Section of petrified cedar wood. 

 H. F. Wegener. 



6. Section of kidney of kitten. A. 

 W. Chamberlin. 



Some of these preparations are very 

 poor, and we trust the preparers will 

 send in more creditable work next 

 time. A little more care and neat- 

 ness in mounting as well as in pre- 

 paring the specimens is desirable. 



Box Cz, containing two of Cole's 

 preparations, came to hand April 

 34th. The subjects are sections of 

 human cerebrum and cerebellum. 



Box G came to hand May 24th with 

 six excellent preparations. 



1. Ureter of hog. Dr. W. H. Cur- 

 rier, showing fibrous outer coat and 

 inner mucous coat with epithelium. 



2. Utricularia. HenryM. Brown. 

 A fine preparation by Mr. L. R. 

 Peet, of Baltimore, who was one of 

 the most expert preparers of stained 

 vegetable specimens. The colors in 

 this preparation are still excellent. 

 This plant is said to catch and kill 

 young fishes.* 



3. Section of small intestine of cat. 

 Rev. E. C. Bolles. 



4. Caprella geometrica. Rev. J. 

 D.King. A fine prepai-ation. 'The 

 slide was mounted some years ago, 

 before anything was said about mount- 

 ing without pressure.' It is a balsam 

 mount of first-class character. 



5. Transverse section of petiole of 

 Brasenia pel lata. N. N. Mason. 

 Two very excellent, well-stained sec- 

 tions. The starch in the cells shows 

 beautifully with the polariscope. 



6. Spores and elaters. Miss M. 

 A. Booth. An interesting prepara- 

 tion, showing well the structure of 

 the elaters. 



Silvering Glass Reflectors. — 

 We promised long ago to give a 

 process for silvering mirrors in these 

 columns, but hitherto we have not 

 been able to refer to some notes of 



• Vol. V, p. 130. 



experiments, which we desired to use 

 in writing up the subject. 



There being no immediate prospect 

 of finding them, we now give a for- 

 mula, which is practically the same 

 as we have successfully used. It is 

 the same as Mr. John Browning rec- 

 ommends for silvering glass specula 

 for telescopes. 



The glass must first be thoroughly 

 cleaned. Plunge it into nitric acid, 

 and in a few moments wash thorough- 

 ly in clean water. Then polish it 

 with putty-powder. It is then ready 

 to receive the coating of silver. 



Make three solutions composed as 

 follows : — 



A. Silver nitrate 45 grains. 



Water 2 ounces. 



B. Caustic potassa (by 



alcohol) ^ ounce. 



Water 12 ounces. 



C. Milk sugar ^ ounce. 



Water 5 ounces. 



Take one ounce of solution A and 

 add solution of ammonia to it drop 

 by drop, with constant stirring, until 

 the dark-brown precipitate at first 

 thrown down is dissolved in a slight 

 excess of ammonia. Add now to 

 this 2 ounces of solution B. This 

 will produce a precipitate, which 

 must be redissolved as before by the 

 careful addition of ammonia. Now 

 make up the bulk of the solution to 

 8 ounces by the addition of water, 

 and in order to neutralize any excess 

 of ammonia that may be present add 

 ■ a few drops of solution A, until a 

 slight precipitate thus formed does 

 not redissolve. Then add 7 ounces 

 of water. Set the solution aside to 

 settle, and then pour oft" the clear 

 fluid. 



When ready to silver the cleaned 

 glass, mix a sufficient quantity of the 

 solution as prepared above with one- 

 fifteenth its volume of solution C, 

 (15 oz. to I oz.), and pour the mix- 

 ture into a shallow dish in which the 

 glass to be silvered is supported, face 

 down. The silver will then be slowly 

 deposited upon it, the rapidity vary- 

 ing with the temperature. It may 



