54 HOW TO WORK 



\\Mter be mixed with spirit, a precipitation of some of the salts 

 dissolved in it not unfrequently takes place, which renders the mixture 

 turbid and unfit for use. Proof spirit will be strong enough for all 

 general purposes, except for hardening portions of the brain or nervous 

 system, when stronger spirit must be used. Two parts of rectified 

 spirit, about sp. gr. '837, mixed with one part of pure water, make a 

 mixture of sp. gr. -gi^-'g2o, which contains about 49 per cent, of 

 real alcohol, and will therefore be about the strength of proof spirit. 

 One part of alcohol, sixty over proof, to five parts of water, forms a 

 mixture of sufficient strength for the preservation of many substances, 

 and not a few microscopical specimens may be preserved in a so- 

 lution more diluted than this. For some years past, the Government 

 has permitted the use of methylated alcohol for various purposes in 

 the arts, which pays no duty. This spirit answers well for preserving 

 anatomical preparations, and is a great boon to all engaged in putting 

 up large anatomical specimens. It may be obtained at the price of 

 5-r. 6d. a gallon, sixty degrees over proof, of Messrs. Lightly and 

 Simon, and of other distillers, in quantities of not less than ten gallons 

 at a time. In the first instance, application must be made to the 

 Board of Inland Revenue, Somerset House, for permission to use 

 the spirit, by letter, accompanied with the names of two respectable 

 householders, who are willing to act as bond that the applicant only 

 uses it for the purposes stated in his application. The probable 

 quantity required annually must also be stated. 



100. Glycerine. This is one of the most valuable fluids ever 

 employed for microscopical purposes. I believe Mr. Warington, of 

 Apothecaries' Hall, was the first observer who used this medium 

 as a preservative fluid for microscopical preparations. 



A solution of glycerine adapted for preserving many structures is 

 prepared by mixing equal parts of glycerine with camphor water. The 

 latter prevents the tendency to mildew, or it maybe mixed with naphtha 

 and water, or with the creosote solution to be described presently. 

 The degree of dilution will depend upon the nature of specimen. 

 If the substance be at all opaque it will be necessary to employ strong 

 glycerine. I have many preparations which have been preserved 

 in glycerine for nearly twenty years. Of the importance of strong 

 glycerine as a preservative medium, I shall have to speak more fully 

 in part V. Glycerine may be mixed with various chemical tests and 

 preservative substances, for special enquiries, and analyses may be 

 conducted by the test substances being dissolved in this menstruum 

 instead of in water. For preserving medusae and delicate marine 

 animals Dr. Carpenter recommends a solution composed of sea water 

 with one-tenth of alcohol and the same quantity of glycerine. 



