and Laboratory Methods. '2647 



requires 5(10 grams of lime per litre, or about four pounds of lime per gallon of 

 alcohol. 



Directions for operating the apparatus : The boiler is three-fourths filled 

 with lime and 95 per cent, alcohol, placed in the water bath, tightly connected 

 with the condenser and allowed to stand over night. On the following morning 

 the bath is heated to, and kept at. about 90° to 93° C. During the first two or 

 three trials the stove must be regulated by the stop-cock in the gas stove, keep- 

 ing the valve at the gas main open full. When the gas supply has been regulated 

 the valve in stove must remain untouched. The supply of water is regulated by 

 the valve at D, keeping the valve on the water main open full. In this way when 

 the apparatus is to be used instructions are to put — grams or pounds of lime 

 and — quarts of 95 per cent, alcohol in boiler, tightly connect boiler and con- 

 denser, close valve I, allow to stand over night, in morning open water main 

 valve and gas main valve full, light stove ; in afternoon, shut off gas and water ; 

 next morning open water main and gas main valve full, light stove and open 

 valve I. When alcohol ceases to flow into absolute alcohol receiver remove and 

 tightly cork the absolute alcohol and immediately clean the boiler. If the lime 

 is allowed to remain in boiler it may be difificult to remove. 



Cost of absolute alcohol made in this way is about as follows. From 50 to 

 75 per cent, of 95 per cent, alcohol is recovered as absolute : 



1 gallon absolute costs, 



2 gallons of 95 per cent., at 50 cents, . . . . $1.00 

 8 lbs. of lime at from 3 to 4 cents, . . - . .24 

 About 100 ft. gas, -.----.. .15 

 Water, about - - .10 



$1.49 



The cost in 95 per cent, alcohol depends on the care in operating. If too 

 much heat is used the loss will be greater. During the first day the alcohol need 

 not boil, as a temperature near the boiling point will complete the reaction. 



This still may also be used for making extracts, etc., and can be made of any 

 desired capacity. 



If the trap pictured in Fig. 3 be blown in a glass tube which could be con- 

 nected with an ordinary Liebig's condenser a very convenient chemical apparatus 

 would be had. 



A number of these stills have been manufactured by Vaile & Young, 210 N. 

 Calvert street, Baltimore, at a cost of about $25 each. 

 Missouri State University. W. J. CalveRT, M. D. 



Preparing Microscopic Plants and Animals for Student Use 



in the Laboratory. 



Smear a glass slide with albumen fixative, as in preparing for the mounting 

 of paraffin sections. Then place on the surface of the film of fixative a drop or 

 two of water containing the forms which it is desired to stain. Let nearly all of 

 the water evaporate by exposure to the air of the room until only the film of 

 fixative remains moist. The slide can now be immersed in Gilson or any other 

 fixing reagent, and then passed through alcohols, stains, etc., in the same way 

 that mounted sections are handled. 



I have had no difficulty in getting preparations of Paramoecium by this 

 method, with very little distortion of the body, and any kind of staining desired. 

 By this method students can prepare in ten minutes very satisfactory preparations 

 of Protozoa for demonstration of nuclei, etc. Harris M. Benedict. 



University of Cincinnati. 



