227 



On a New Form of Deep Cell, made by the Tilghman 

 Patent Sand Blast Process. 



By Henry F. Hailes. 



(Read January 23rd, 1874.) 



I wish to call the attention of the Club to what I may term 

 another solution of the great cell difficulty ; it remains to be seen 

 whether experience will justify me in calling it an improvement. 



Those who have tried mounting in balsam with any of the ordi- 

 nary cells must have found that it is by no means an easy task to 

 perform satisfactorily. 



The fact of there being two joints — one where the cell is attached 

 to the slide, and the other where the cover is joined to the cell — is a 

 great source of trouble, air bubbles being very apt to find their way 

 in either at one or the other of the joints. 



Perhaps the best forms of cell that have as yet been devised 

 are those ground out of the slide itself ; but these, as hitherto made, 

 are open to several objections — they are either very shallow, or very 

 large, or both — the object is very apt, either in the process of 

 mounting or afterwards, to shift to one side or the other, and to get 

 wedged in between the cover and the bottom of the cell. 



It occurred to me that possibly the Patent Sand Blast process 

 might be turned to account for this purpose, and having the advan- 

 tage of knowing the inventor. General Tilghman, I got him to have 

 a few slides sunk for me as an experiment, and these slides proving 

 satisfactory, as far as I could judge, I made an arrangement with 

 him to supply me with a quantity of them, with cells of various 

 sizes and depths. The cells may by this process bo sunk into the 

 slide any required depth or shape, irrespective of the sizes, which 

 may^also be varied. I find]^a small, deep cell, about one-fifth of an 

 inch in diameter, very useful for mounting Foraminifera. An object 

 can be put under the centre of the slide, covered, and hardened off 

 without any risk of shifting; and even if the balsam does not get 

 quite hard in the cell, the object can never get out of its place. 

 Of course the Sand Blast process leaves the cell in a rough, or 

 JouRN. Q. M. C, No. 26. p 



