ON FRESEUVATIVE FLUIDS. 281 



We are told that Mr. J. T. Cooper,* in the course of a series 

 of experiments to determine the best fluid for preserving 

 coloured tissues, also found that salt and water, to which 

 acetic acid had been added, succeeded extremely well for this 

 purpose ; such a mixture will also answer for most minute 

 vegetable tissues. The great objection to the use of all saline 

 fluids is the growth of confervse which takes place in them; 

 this may, in a great measure, be avoided by the addition of. 

 a few drops .of creosote, or a small quantity of camphorated 

 water. 



Naptha. — This, when mixed in the proportion of one part 

 to seven or eight of water, will make a good preservative 

 solution; the author, by accident, having placed in water 

 some portions of skin to macerate, that had been coarsely 

 injected with a material into which naptha entered rather 

 largely as an ingredient, was surprised to find them perfectly 

 free from decomposition even after the lapse of many weeks; the 

 water was impregnated with naptha, and the specimens were in 

 excellent condition, having undergone little or no change. 



General Directions. — It may here be stated, that for all large 

 specimens, such as injections, the spirit and water, or 

 Goadby's first solution, may be used ; and for others, either 

 the creosote or glycerine solutions, as those containing saline 

 matter, when placed either between glasses simply, or in the 

 thin glass cells, are apt to crystallize slowly, and interfere 

 with the objects that are mounted in them. Goadby's solu- 

 tion, containing salt, alum, and -corrosive sublimate, will keep 

 animal structures that have been injected with size and ver- 

 milion exceedingly well ; but those in which the vessels are 

 filled with flake-white will have that substance destroyed in a 

 few hours; in these cases, either the arsenical or the spirit and 

 water only should be employed. The glycerine fluid, when 

 kept for some time, is apt to become mouldy; it should, there- 

 fore, be mixed in small quantities, and then only a few hours 

 before it is required. When objects are to be mounted in 

 either of the above fluids, it must be laid down as a rule that 

 they should have been soaking for some hours in the same 

 * Microscopical Journal, vol. i., page 184. 



