V8 



REPOllT — 1889. 



B A 



overcome these same difficulties, but not with perfect success. I at that 

 time made use of osmosis, and invented several instruments, all in some 

 degree resembling that of which Schultze has more recently given a 

 description. The apparatus was, however, complicated, and therefore 

 difficult to prepare as well as to use, the method tedious, and the results 

 not altogether satisfactory. 



The importance of the matter being once more brought home to me, 

 I determined to see whether it was not possible, by some simple means, 

 to attain the desired result, and to devote, if necessary, a long time to 

 experiments directed towards that end. Fortunately I soon hit upon a con- 

 trivance which, while it is extremely simple, is correspondingly efficient. 

 Without burdening this report with an account of my more or less 

 unsuccessful experiments, I will proceed at once to describe this simple 

 and efficient instrument which has rendered me such good service. It is 

 made from glass tubing, which may vary in intei'nal diameter from 3 mm. 

 to -g- cm. or more. The instrument is double in its nature. If the objects 

 arebeing transferred from a heavy fluid to a lighter, Form A is used ; if 

 from a light fluid to a heavier, Form B is used. 



Bach form consists of three pieces of tubing, bent as shown in the 

 ficrures. Two of the pieces, h and c, are common to both forms, a and a' 

 differ from each other in that a' is longer, and is doubled 

 on itself below, I will call a and a' reservoirs ; h the 

 object-hox or object-cylinder ; and c the filter. All are 

 shown in position m the figures. In use the object- 

 box is joined to the reservoir and filter by rubber tub- 

 ing, which, for the sake of simplicity, is not shown in 

 the figures. The termination of the filter c is made 

 into a capillary tube having an internal diameter of "1 

 to '2 mm. 



The object, supposed to be previously fixed in sub- 

 limate or other fixing agent, is placed in the object-box 

 in some of the fixing fluid, and is kept in place by 

 plugs of cotton, asbestos, shreds of linen, or other 

 similar material. The filter is also filled with the fix- 

 ing fluid, and it will be found best to insert here also 

 a plug of cotton, otherwise particles of carmine, &c., 

 may stop up the terminal capillary part. The filter 

 and box are now joined together by rubber tubing, no 

 bubbles being admitted. To avoid bubbles in the 

 cotton, boil it, or soak it in alcohol and rinse in water. 

 Suppose now the object has been fixed in subli- 

 mate, and is to be mounted in balsam after straining 

 in borax carmine. I bring the object first into 'SO per 

 cent, alcohol, a lighter fluid, as follows : 



The box and filter, joined together as just des- 

 cribed, are connected with a reservoir as in A. The 

 reservoir is then filled to 1 with 5 per cent, alcohol, 

 from 1 to 2 with lu per cent, alcohol, from 2 to 3 with 

 15 per cent., from 3 to 4 with 20 per cent., from 4 to 5 with 25 percent., 

 and from 5 to the top with 30 per cent. By taking sufficient care these 

 different alcohols may be allowed to flow in that they will remain distinct 

 from one another, or they may be run in so forcibly that the whole 

 contents of the reservoir will be a nearly uniform mixture of about 15 



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