228 



THE AMERICAN MONTHLY 



[December, 



heavy glass slides, and put aside to 

 harden for one hundred and three 

 days. The slides with rings were 

 put into a rigid frame, supporting 

 them at both ends, and a hook, with 

 a deep pan attached, was slipped into 

 the loops of brass wire. Sand was 

 cautiously poured into the pan, and 

 when enough had been added to 

 occasion the breaking apart of ring 

 and slide, the quantity added was 

 carefully weighed, and the condition 

 of the cement noted, with the follow^- 

 ing results : — 



1000 



735 

 664 

 626 

 575 

 532 

 395 

 304 

 241 



By calling Miller's cement 1000 we 

 have the following table representing 

 the comparative adhesiveness of the 

 cements tested : — 



Miller's caoutchouc cement, 

 Bell's cement, - - - - 

 Canada balsam, ... 

 Lovett's cement, ... 

 American styrax, 

 King's cement, - . . 



Gold size, - . . . 

 Dissolved marine glue, - 

 Zinc white cement, 



Gold size would undoubtedly have 

 stood much higher in the list had it 

 been sufficiently hardened. It cer- 

 tainly showed considerable tenacity 

 when the fact that the edges only 

 were hard is taken into consideration. 

 Most of the other cements were dry 

 enough to make the results sufficiently 

 accurate for comparison, 



R. Miller's caoutchouc cement is of 

 English manufacture, and is well 

 recommended. Having only used it 

 for a short time I cannot say much in 

 regard to its qualities from personal 

 observation. 



Bell's cement is said to be a solu- 

 tion of shellac in alcohol. It has al- 



ways worked well in my hands for 

 glycerin, camphor, water, and some 

 other liquid media. 



Canada balsam I have only used as 

 a mounting medium, and should fear 

 that it might become too brittle in 

 time to be reliable as a cement. 



Lovett's cement* consists of thor- 

 oughly mixed, finely powdei^ed white 

 lead 2 parts, red lead 2 parts, lith- 

 arge 3 parts. For use the powder is 

 mixed with gold size to the consist- 

 ency of cream, and the cells imme- 

 diately fastened to the slides. They 

 will be found quite secure in two 

 weeks. It is the best cement I know 

 of for liquids containing alcohol. 



American styrax is an excellejit 

 mounting medium. It would proba- 

 bly remain tough longer than Canada 

 balsam. I have never used it as a 

 cement, however. 



King's cement, prepared by J. D. 

 King, Cottage City, Mass., I have 

 found to be a pleasant cement to finish 

 mounts with. The label states that 

 it is ' strong and reliable to attach 

 cells and secure fluid mounts.' 



The gold size I use is of Winsor 

 & Newton's make, it dries rapidly 

 and is very tough ; my experience 

 with it is such that I consider it one 

 of the safest, if not the safest, of our 

 common cements. Cells made many 

 years ago, which have been roughly 

 handled, show no tendency to crack 

 or loosen. 



Dissolved marine glue is a fusel oil 

 (amylic alcohol) solution put up by 

 Robert Howard, of Birmingham, 

 England. The label states that it is 

 ' very good for fixing cells, or making 

 zoophyte troughs, etc' My expe- 

 rience with it is so limited that I am 

 unable to say anything additional. 



The zinc white cement (benzole 

 solution of gums) was prepared by 

 Geo. F. H. Markoe, 61 Warren 

 street, Boston, Mass. I like this 

 cement very well for dry mounts, but 

 have always been in the habit of cov- 

 ering it with a ring of gold size. 



* Vol. V, p. 98. 



