1040 RECORD OF CURRENT RESEARCHES RELATING TO 



the object itself or from the mountirig material. In the case of such 

 objects as Polycistina and diatoms which have been exposed to low 

 red heat, it is unlikely that any vapours would ever be given off, and 

 slides of these objects have been found both with dew and free from 

 it. A good deal probably depends upon the quality of the wax and 

 the processes used in bleaching it. Where bleached by exposure to 

 sunlight and water, and afterwards carefully melted, it is believed no 

 vapour will be given off. Where the wax has been bleached by 

 the action of acids and chlorine it is difficult to tell what changes may 

 occur. 



Amongst the directions for mounting in wax cells, one which has 

 been generally given and very usually followed, is to soften the wax 

 with turpentine at the point where the object is to be placed. When 

 this has been done, and the cell closed immediately, the turpentine is 

 sure to evaporate and settle on the cover. It there becomes oxidized 

 or ozonized, so that it is no longer volatile, and it was undoubtedly 

 this ozonized turpentine which resisted the high temperature alluded 

 to by Prof. Smith. Instead of turpentine, a copper wire should be 

 used, highly heated, and held near but not in contact with the wax. 



To the same tenor are the remarks of Mr. C. F. Cox and Mr. J. F. 

 Stidham.* The former points out that while if the ground for con- 

 demnation — "dew" on the cover-glass — were found exclusively in 

 the case of wax cells, it might be fair to infer that the cause was the 

 wax, yet as it is found more or less in cells of all kinds, and is not 

 worse in wax cells than in most others, the denunciation by Prof. 

 H. L. Smith of his own invention is not justified. The misty con- 

 densation may possibly be caused in some cases by emanations from 

 the sheet wax, but Mr. Cox's experience goes to prove that it is 

 mainly due to the too free use of cements containing resinous or oily 

 solvents, like turpentine or benzole, though sometimes it may arise 

 from the want of dryness in the object itself, or a recrystallization of 

 chemical constituents of the cements, as the Professor suggests. If 

 a cement is used, composed of shellac dissolved in alcohol, plenty 

 of time allowed for the completion of each step, no more cement used 

 than is necessary, and the sj)ecimen itself thoroughly dry, the cell will 

 be free from vapour and condensations, and he is therefore of opinion 

 that the wax cell is "the best cell for dry objects that has ever been 

 used." 



Mr. Stidham's testimony is to the same effect. He " has found 

 no trouble since covering the whole cell with a thin film of shellac, 

 and using shellac to fix the cover, provided the day was a dry one, 

 and the cover is held for a moment over the lamj) flame." He thinks 

 Mr. C. C. Merriman's suggestion of leaving a small opening so that 

 moisture may get out would be of practical advantage if it can be 

 done. 



Improvement in Making Wax Cells.! — For making wax cells, 

 when they are wanted smoother and handsomer than they can be made 

 with a punch alone, Mr. J. D. White recommends the following 



* • Am. Journ. Micr.,' v. (ISSO) p. 207. 



t ' Am. Mon. Micr. Journ..' i. (1880) p. 150-1. 



