62 



EXPERIMENTAL PHARMACOLOGY 



Defai/cfffack 



Fig. 56. Automatic shellacing pan and drying rack for drum records. \ arnish is 

 made by dissolving the best granular zclutc shellac in alcohol. A large excess of the 

 shellac should be present, and solution is allowed to go on for a week or more (shake 

 up thoroughly several times), at the end of which time the clear supernatant solution 

 is decanted and placed in a well stoppered bottle to prevent evaporation of the alcohol. 

 If this occurs small particles of the shellac precipitate out and may spoil the varnished 

 records by being deposited as white specks all over the black surface of the tracing. 

 Orange shellac is somewhat more soluble than the white but not so satisfactory because 

 of the yellowish color it gives to the records. This is very undesirable if any records 

 are to be blue-printed, photographed or used for publication. Cheap varnishes made 

 of gasoline and rosin, etc., are sometimes used. A high grade brass lacquer (such as 

 Kahlbaum's metallfurniss, farblos) may often be much diluted with alcohol and thus 

 made into an excellent varnish for records. 



