SCHALLIBAUM'S COLLODION METHOD. 213 



It is sufficient to hold the slide over a spirit lamp until the 

 paraffin has melted and the clove oil has collected in drops 

 between the sections. Schallibaum has stated elsewhere that 

 long evaporation of the slide is necessary if the sections are 

 to be secured firmly enough to allow of staining on the slide. 

 That is not so. What is necessary is that the paraffin and 

 clove oil be thoroughly removed from contact with the sec- 

 tions ; and that can be done in a second (as was shown me by 

 Professor v. Korotneff). Warm the slide over a flame, and 

 whilst the paraffin is still melted hold it close before your lips 

 and blow down on it vigorously. The paraffin and clove oil 

 are scattered right and left over the slide, leaving the sections 

 high and dry. 



Personally I do not consider Schallibaum' s method so safe 

 as Mayer's albumen (and some other methods) for objects 

 that are to be stained on the slide. I recommend it for 

 already stained objects, because it is found to work very 

 pleasantly. Its great defect is that it does not readily lend 

 itself to any device for the flattening out of folded sections. 

 I recommend xylol or naphtha for clearing, in preference to 

 turpentine. 



Good collodion is essential in this process. 



STRASSEE (Zeit. f. wiss. Mik., iv, 1, 1887, p. 45) recommends 

 a mixture of 2 parts collodion, 2 parts ether, and 3 parts 

 castor oil; or (ibid., vi, 2, 1889, p. 153) 2 parts of collodion 

 with one of castor oil, the sections being painted over with a 

 thicker solution, viz. collodium concentratum duplex 2 to 3 

 parts, castor oil 2 parts, and the slide being plunged at once, 

 without warming, into a bath of turpentine, in which it 

 remains till the paraffin is dissolved (two to ten hours, some- 

 what less if the whole be put in a stove) . The turpentine 

 suffices to harden the collodion (benzin, benzol, and chloro- 

 form have the same effect) . 



GALLEMAEETS (Bull. Soc. Beige de Micro., xv, 1889, p. 56; 

 Zeit. f. wiss. Mik., vi, 4, 1889, p. 493), following DEASH, em- 

 ploys a saturated solution of gun-cotton in acetone, diluted to 

 the requisite thinness with absolute alcohol. 



GAGE prefers preparing slides with a layer of pure collodion, 

 which is allowed to dry, and is rendered adhesive at the instant 

 of using by brushing with clove oil. 



SUMMEES (Amer. Hon. Mic. Journ., 1887, p. 73; Zeit. f. iviss. 



