1885.] 



MICKOSCOPICAL JOURNAL. 



39 



to us as follows : 'It is the finest glass I 

 ever saw, beats Powell's ^V quite away — 

 is the admiration of everyone.' 



CORRESPONDENCE. 



White Zinc Cement. 

 To THE Editor: — I have been an in- 

 terested reader of all that has appeared in 

 the Journal, both pro and con, concern- 

 ing the use of white zinc as a cement in 

 dry mounts. And I mail to you herewith 

 four slides of dry mounts which, with the 

 two pre\iously sent, please add to your 

 collection, with a view to testing the reha- 

 bleness of the cement. In common with 

 many preparers, I have been disgusted 

 with the amount of trash in circulation 

 as exchanges, and have not always found 

 the work of even professional preparers 

 infallible as to running in. So, when I 

 commenced mounting, I was the more 

 determined that none but first-class, dura- 

 ble work should leave my hands. White 

 zinc was the cement I selected for dr)- 

 mounts of diatoms, etc., and I have never 

 had occasion to regret my choice. My 

 experience has been that white zinc ce- 

 ment properly prepared, not the work of 

 a tyro, the rings to be made at least 48 

 hours, and preferably several weeks in 

 advance, will not run in. I shall regard 

 it as a favor if any person who has re- 

 ceived any of my slides, either by pur- 

 chase or exchange, which have not kept 

 well will return such slides, and I will 

 cheerfully replace them with perfect slides. 



M. A. Booth. 

 LoNGMEADow, Mass. 



[It would afford us great pleasure to 

 testify to the excellence of the preparations 

 kindly sent by our correspondent could 

 we do so conscientiously. Unfortunately 

 they are all defective, and the specimens 

 are already ruined. The white zinc ce- 

 ment has been unable to withstand the 

 conditions incident to travel. Every slide 

 was literally smashed to pieces, so that 

 the glass was almost powdered. 



As regards the different experiences of 

 workers with this cement, however, there 

 is this much to be said : That if one has 

 time enough to wait for a cement to 

 harden thoroughly any of the cements in 

 common use will undoubtedly serve per- 

 fectly well. We have no more doubt of 

 the possibility of making durable mounts 

 with white zinc cement than we have that 

 they could also be made with gold-size, 

 which eventually would dry hard and 

 never run in. It is purely a matter of 



time in this case. The point we have 

 urged against the use of white zinc is not 

 that it is impossible to use it successfully, 

 but that, as experience has shown, in the 

 hands of a considerable number of work- 

 ers it is unreliable. Contrary to the opinion 

 of a somewhat discourteous critic, our 

 opinions upon this matter are not based 

 upon what we ha\'e done so much as 

 upon what we have seen of the works of 

 others ; so that we have discarded it for 

 our own use. The trouble is that we — 

 like many other workers — must work 

 rapidly, and a cement that hardens slowly 

 will not do. Thus, on Christmas day we 

 found a specimen of such interest that we 

 wished to send a mounted preparation 

 abroad. By the use of shellac, on a per- 

 fectly plain slide, a ring was made, the 

 specimen mounted within it in water, and 

 sealed up within ten minutes, and had we 

 not wished to put a ring of black varnish 

 on it the preparation could have been 

 safely mailed the same evening, and we 

 could gurantee it against running in or 

 leakage. Quick and sure work like this 

 is impossible with the white zinc cement. — 

 Ed.] 



Mounting Urinary Deposits. 



To THE Editor: — ^In response to the 

 inquiry of your correspondent, in the De- 

 cember number of the Journal, I offer 

 the following formula for a mounting 

 fluid for urinary deposits : Glycerin and 

 distilled water each four fluid drachms, 

 chloral hydrate five grains, creosote five 

 drops, gum camphor two grains. Mix, 

 shake thoroughly, and filter. 



As far as I have tried this, it preserves 

 epithelium, casts, and to a limited extent 

 crystals. 



To prepare casts, place the urine in a 

 conical vessel, and when the sediment is 

 well settled remove the supernatant fluid 

 with a syphon, dilute the sediment with 

 distilled water, let settle, and again re- 

 move the supernatant fluid as before, and 

 repeat as often as is necessary. When 

 the sediment containing the casts is suffi- 

 ciently clean, add to it a few drops of car- 

 mine solution, let stand five or ten min- 

 utes, again dilute with an equal amount 

 of distilled water, and remove the super- 

 natant fluid down to the sediment. Now 

 add of the mounting fluid above named a 

 quantity equal to that of the sediment, 

 and mount in cells made by running 

 rings of asphaltum on clean slides. If 

 used within half an hour any irregulari- 

 ties of their surfaces will yield when the 



