94 THE MICROSCOPE. June 



the slide, and in the case of scales, fix by passing" throug-h 

 the flame. 4. Stain in gfentian-anilin-violet (made in the 

 usual way by the addition of a few drops of saturated al- 

 coholic solution of g-entian-violet to anilin-water ), fifteen to 

 sixty minutes. 5. In Gram's iodine solution one to five 

 minutes. 6. Decolorize in anilin-oil two or three hours or 

 long-er. 7. Remove anilin-oil by blotting- paper and mount 

 in Canada balsam. — St. Loids Med. a'ld Suri^ical Journal. 



Perservation of Mucilages and Pastes. — Considerable 

 has been written from time to time about preservation for 

 mucilag-es and pastes. Oil of cloves, creosote, carbolic 

 acid, and various other thing-s have been recommended, 

 but none of them in my experience has served the purpose, 

 and the paste-pot in the g-reat majority of instances, is far 

 from sweet-smelling-. 



For the use of the pharmacist a nicely made flour paste, 

 in my opinion, is the most desirable adhesive that can be 

 used; but unfortunately it is very prone to sour. Starch 

 paste, even with the addition of g-lycerin, soon sours and 

 becomes useless. In places where considerable quantities 

 of paste are used this is not a matter of so much conse- 

 quence, for it can be made in such amounts that it will be 

 used up before it spoils, but to the retail pharmacist wish- 

 ing- to use it for his labels or to the photog-rapher using- it 

 for his mounting-, it is dilferent, and so many have adopted 

 the expedient of buying- the patent pastes of the market. 



Stepping- into a leading- drug- store not long- agfo, I noticed 

 a bottle of library paste sitting- on his prescription case. 

 I asked the proprieter whether he liked it better than flour 

 or starch paste. No, he said, but he knew of no way of 

 keeping- these from souring-, and so had been using- the 

 patent article. With a view of overcoming- this difficulty 

 I beg-an a line of experiments during- the month of Nov- 

 ember last, but failed to find anything- that proved satis- 

 factory for sixty or ninety days. When about to quit in 

 disg-ust, the thoug-ht struck me that perhaps formaldehyde 

 was the ag-ent I was looking- for. In order to g-ive this 

 ag-ent as thoroug-h a test as possible I made the following- 

 experiments and numbered them in the order made and 



