149 



Note on a Spirit-Proof Micro-Cement. 

 By Charles F. Rousselet, F.R.M.S. 

 {Read June 2\st, 1895.) 



Everyone here will know the great importance of a thoroughly 

 reliable cement for fluid mounts. All cements which become quite 

 dry and hard in time are then also slightly porous, and allow the 

 fluid to evaporate slowly through the pores. Asphalt, on this 

 account, is quite useless for fluid mounts, and even Miller's 

 caoutchouc cement can only be depended upon for a time. After a 

 few years it becomes quite dry, and sooner or later an air bubble 

 appears in the mount. 



It is my pleasure this evening to announce the discovery of a 

 cement which is not only reliable for objects in watery fluids, but 

 which will also keep in permanently strong and even absolute 

 alcohol. I do not mean to imply, however, that I have myself 

 discovered the cement in question. I have only discovered its 

 existence, which seems almost as great a merit, for it has been 

 used by some for the last fifteen or sixteen years, and yet the fact 

 of its existence has not penetrated to our Microscopical Societies in 

 London. Dr. Dallinger's " Carpenter " recommends the periodical 

 addition of a layer of cement to prevent its becoming quite dry, 

 and only knows Lovett's a very troublesome cement for spirit 

 mounts. Mr. Bolles Lee, in his latest (1893) edition of the 

 " Microtomist's Yade Mecum," says, in speaking of alcohol as a 

 preservative fluid : " Not very recommendable for mounting, as if 

 taken weak it is not a very efficient preservative, and if taken 

 strong it attacks tbe cement of mounts." 



The cement which I wish to bring before you is called Clarke's 

 Cement, and has been used by Mr. Thos. Clarke, of Birmingham, 

 for the last sixteen years for mounting objects in methylated 

 spirit, and his slides are quite good and sound now. I have here 

 a slide of Leptodora hyalina mounted in alcohol by this gentleman 

 in 1887, or eight years ago, and it is perfect at present. This is 

 sufficient proot that the cement is leliable for spirit mounts, and, 



