98 COLLODION AND OTHER IMBEDDING METHODS. 



APATHY (Mikrotechnik, p. 121) holds that it is preferable to 

 transfer to fresh thick solution, as he finds that a better consistency 

 after hardening is thus obtained. 



160. Imbedding. The objects must now, if it. has not been done 

 before, be imbedded that is, arranged in position in the thick 

 collodion in the receptacle in which they are to be hardened. For 

 the usual manipulations see 137. If paper thimbles be taken for 

 imbedding, the bottoms should be made of soft wood in preference 

 to cork. See 165. They should be prepared for the reception of 

 the object by pouring into them a drop of collodion, which is allowed 

 to dry. The object of this is to prevent bubbles coming up through 

 the wood or cork and lodging in the mass. Watch-glasses, deep 

 porcelain water-colour moulds, and the like, also make convenient 

 imbedding receptacles. Care should be taken to have them perfectly 

 dry. 



It not infrequently happens that during these manipulations 

 bubbles make their appearance in the mass. Before proceeding 

 with the hardening these should be got rid of by exposing the whole 

 for an hour or two to the vapour of ether in a desiccator or other 

 well-closed vessel. Care should be taken that the ether (which may 

 be poured on the bottom of the vessel) does not wet the mass (BussE, 

 Zeit. wiss. MiL, viii, 1892, p. 467). 



161. Orientation. Celloidin being more or less transparent, it is 

 seldom necessary to resort to special aids to orientation. 



APATHY (Zeit. wiss. Mik., v, 1888, p. 47) arranges objects on a 

 small rectangular plate of gelatin, placed on the bottom of the 

 imbedding-recipient. The gelatin is turned out with the mass after 

 hardening, and cut with it. The edges of the gelatin form good 

 orientation lines. 



HALLE and BORN (Zeit. wiss. Mik., xii, 1896, p. 364) use plates of 

 hardened white of egg, in which a shallow furrow for the reception 

 of the objects has been cut by means of a special instrument. See 

 also 142. 



For the complicated method of EYCLESHYMER (Amer. Nat., xxvi, 

 1892, p. 354) see previous editions. 



See also the article " Kekonstruction " in the Encycl. mik. Technik. 



162. Hardening, Preliminary. The objects being imbedded, the 

 treatment should be as follows : The receptacles or supports are 

 set with the mass under a glass shade, allowing of just enough com- 

 munication, with the air to set up a slow evaporation. Or porcelain 

 moulds or small dishes may be covered with a lightly fitting cover. 



