CEMENTS, VARNISHES, AND CELLS. 249 



You will notice from these remarks that I am an advocate of 

 the wax cell and shellac varnish. The merits of the latter are 

 now pretty generally known, and if once used it is not apt to be 

 discarded. It must not be trusted to alone, as it will not stand 

 sudden jars. The wax cell is still a disputed subject. I know 

 they are liable to sweat, but I think I can safely hazard the 

 statement that not one dry mount in fifty, not put up in an 

 absorbent cell, will show an unclouded cover after a few years. 

 Objects of the mineral kingdom alone do not give off vapours. 



Again, we must not lay the defects of the cover-glass itself to 

 this cause. If you examine carefully a number of cover-glasses, 

 taken from different packages, you will find quite a proportion 

 show an appearance resembling minute beads of moisture on the 

 surface. This is due to a roughness of the glass, which prevents 

 the light from passing through properly. If such glass is used on 

 balsam mounts the defect is not noticeable, but if used for dry 

 mounts an amount of sweating that would ordinarily be of little 

 moment will so intensify the effect that the mount is declared 

 ruined and the cell gets the blame. My experience with wax 

 cells has been very great, and when carefully prepared I do not 

 think they are any more liable to sweat than any form of cell that 

 is hermetically sealed. If it were possible^ I would put up 

 everything in a solid medium, such as balsam or Farrant's solu- 

 tion. Such preparations will remain long after those dry or in 

 fluid have been thrown away. 



2^2 Thirty-first Street^ Chicago. 



Hardening Brain. ^ — Take a 6 per cent, solution of HNOs ; 

 put the brain or spinal cord in, and leave it for from three to four 

 weeks. I have found it a most excellent method. The brain 

 looks like a papier-mache specimen, and I have one which I have 

 kept over four years without any change m its appearance. — 

 V. A. Latham, B.Sc, KR.M.S., Univ. of Mich. 



