72 APPENDIX TO PART I. 



filtered, and evaporated over the water-bath to the 

 consistency of thick syrup. I call this the " Gram- 

 Riitzou " varnish, after its discoverers. 



I have not personally tested the mastic cement 

 (Maskenlack, No. 3), recommended by German 

 investigators, nor Ziegler's and other foreign com- 

 positions. 1 can, however, recommend the so- 

 called Japan varnish, which seems to me very use- 

 ful for the first coat, when applied similarly to 

 asphalt. 



In the laboratory at Rome a cement is used, 

 prepared by dissolving with the aid of heat 100 

 parts gum dammar in 100 parts benzole, and add- 

 ing 60 parts ivory black ground with oil. 



An alcoholic solution of shellac can be used for 

 fastening the label to the slide, as gums and other 

 adhesive substances do not adhere well to the 

 glass. [Fish glue and the liquid glue made with 

 acetic or nitric acid are useful for this purpose, 

 though rather disagreeable to use. W. T.] 



