Brai?i Preservation 389 



solution, but this is declared by Gierke to be prejudical to the 

 preservation of the tissues. 



Corrosive sublimate is useful as a fixative either in an 

 aqueous or alcoholic solution ; it is more soluble in the latter. 

 Chaussier at the beginning of the nineteenth centurj' recog- 

 nized the antiseptic properties of this salt and since that time 

 it has been quite extensively used as a preservative. Pro- 

 fessor Robert Garner' with regard to his method says : " We 

 let the brain fall from the skull into a hardening solution 

 of bichloride of mercury, the strength about six ounces of 

 the salt to the half gallon of wrater making a fluid of about 

 1.038 sp. gr. or the same as the brain itself, in which it 

 consequently remains suspended in mid-fluid without pressure 

 on any of its surfaces and becoming hard and solid without 

 the contraction which takes place when spirit is used. " 



Richardson'" gives the following formula for the central 

 nervous system ; 



Mercuric chlorid 2 grams 



Alcohol (sp. gr. 83) 90 c. c. 



Hydrochloric acid 2 c. c. 



There are various inconveniences attending the use of this 

 reagent, not the least of which are its corrosive action on 

 anything metallic making it very necessary that all traces of 

 it be washed out before any dissection is undertaken ; its 

 caustic action on the hands is very marked ; precipitates 

 often occur in the tissue and are a source of considerable 

 annoyance to the histologist. Camphor renders the sublimate 

 more soluble and if the tissue after its sublimate bath be 

 brought into alcohol containing camphor the washing out of 

 the salt is considerably expedited. Tincture of iodine is 

 another agent useful in this respect. A little of it is added to 

 the alcohol and as it dissolves out the sublimate, the color of 

 the solution is weakened and the iodine is gradually renewed 

 until the color no longer fades. The alcohol should be 

 changed frequently. If the sublimate is not thoroughl}' re- 

 moved from the tissues thej' become brittle. 



The origin of the use of Zinc chlorid for neurological pur- 

 poses is enveloped in considerable uncertainty. Bischoff* in a 



*Die Grosshirnwindungen des Menschen. Miinchen. i858. S. 11. 



