2440 Journal of Applied Microscopy 



may be used in the same way, but is a little more expensive and does not seem 

 to give any better results. 



The turpentine is now rinsed off with 95 per cent, alcohol — absolute alcohol 

 not seeming to offer any advantages. The alcohol is kept in a bottle with a 

 narrow neck and is poured upon the slide, just as was the turpentine. Two 

 teaspoonfuls, judiciously applied, are usually enough to remove the turpentine. 

 We do not use this alcohol a second time. The slide is now placed directly in 

 any stain, whether alcoholic, anilin or aqueous, without passing through any of 

 the various grades of alcohol. The only alcohols which we now keep in Stender 

 dishes are 50 per cent., 95 per cent., and absolute. The 95 per cent, is retained 

 merely to avoid an unnecessary weakening of the more expensive absolute alco- 

 hol, while the 50 per cent, is used to wash out various stains, like safranin, etc. 



With thick sections this method is not so satisfactory, since plasmolysis may 

 result even in fixed material. We still use a closely graded series of alcohols 

 for hardening and dehydrating material preliminary to embedding in paraffin. 

 University of Chicago. CharleS J. CHAMBERLAIN. 



An Electric Thermostat. 



Last fall the writer had occasion to use a paraffin bath, but had no gas in 

 the laboratory. This led to the construction of an electric heater. After some 

 experimentation, we constructed hastily and rather roughly a thermo-regulator. 



Fig. 1. — Photograph showing the thermostat as used in heating a paraffin bath. 



that we have used and found to be fairly sensitive. We were able to keep the 

 temperature from varying more than }:l of a degree C. By making the mercury 

 cistern larger, there seems to be no reason why the variation may not be reduced. 



