COLLODION AND OTIIE!: IMBEDDING METHODS. 10o 



once in ether, or a mixture of ether and alcohol, to make a 

 collodion of any desired strength. But it is better, as 

 recommended by APATHY, to cut them up into thin shavings, 

 which should be allowed to dry in the air until they become 

 yellow, transparent, and of a horny consistency, and that these 

 be then dissolved in alcohol and ether (sulphuric, free from 

 acid). The solutions thus prepared are free from the excess 

 of water that is present in the undried celloidin, and give 

 after hardening a mass that is more transparent and of a better 

 consistency for cutting (Zeit. wiss. Mik.jVi, 1889, p. 164). 



Imbedding masses of excellent quality can be prepared 

 with ordinary collodion, but celloidin furnishes more readily 

 solutions of known concentration. Otherwise there is but 

 little to choose between the two, and therefore in this work 

 the terms collodion and celloidin are used indifferently. 



According to UNNA (Monatschr. p. Dermatol., xxx, 1900, pp. 422 and 

 476; Zeit. wiss. Mik., xviii, 1901, p. 32) a more inelastic, and therefore 

 better, mass is obtained by adding to celloidin 2 per cent, of oil of 

 turpentine, stearate of soda, or (best of all) castor-oil. Celloidin with 

 this addition has been put on the market under the name of " Celloi- 

 dmum inelasticuni," by the Chemische Fabrik vorm. E. ScJicriny, in 

 Berlin. 



Photoxylin (KRYSINSKY, YIRCHOW'S Aicliiv, cviii, 1887, p. 217; 

 BUSSE, Zeit. iviss. Mik., ix, 1892, p. 47) is a dry substance, of the aspect 

 of cotton-wool, and chemically nearly related to celloidin. It can be 

 obtained from GRUELER. It gives a clear solution in a mixture of 

 equal parts of ether and absolute alcohol, and should be used in exactly 

 the same way as celloidin. It has the advantage of affording a mass 

 which after hardening in 85 per cent, alcohol remains perfectly trans- 

 parent. Some writers say that it gives a better consistency, but others 

 deny this (APATHY, e.g.). 



TSCHERNISCHEFF (Zeit. wis*. Mik., xvii, 1900, p. 449) recommends 

 Colloxylin (10 grins, dissolved in 10 grins, of engeiiol or clove oil, with 

 the addition of 50 c.c. of ether and 1 of absolute alcohol). 



The Older Celloidin Method. 



158. Preparation of Objects. The objects must first be 

 very thoroughly dehydrated with absolute alcohol. They are 

 then soaked till thoroughly penetrated in ether, or, which is 

 better, in a mixture of ether and absolute alcohol. DUVAL 

 (lor. cif.) takes for this purpose a mixture of ten parts of 

 ether to one of alcohol ; SCHIEFPERDKCKEE (and the majority 



