25 



Solvents and Oils 



Decimal Divisions Used in Chapter 



S 00 GENERAL OBSERVATIONS 



S 10 DEHYDRATING AGENTS (e.g. solvents miscible with water, but not with wax, 



embedding media, or resinous mounting media) 



S 11 Table of physical properties of dehydrating agents 

 S 20 "CLEARING" AGENTS (e.g. solvents not miscible with water, but miscible with 



either wax, embedding media, or resinous mounting media) 



S 21 Table of physical properties of essential oils 



S 22 Table of physical properties of synthetic reagents 

 S 30 "UNIVERSAL" SOLVENTS (e.g. solvents miscible both with water and with 



either wax, embedding media, or resinous mounting media) 



S 31 Table of physical properties of "universal" solvents 

 S 40 RECOMMENDED MIXTURES 



S 41.1 Formulas 



S 00 General Observations 



Solvents and oils are used in micro- 

 scopical technique principally for the pur- 

 pose of preparing objects for mounting 

 whole in resinous media (Chapter 6) or 

 for section cutting after embedding in one 

 of the ways discussed in Chapters 12 

 through 15. At one time these reagents 

 and mixtures of them could be clearly 

 divided into two groups: those intended 

 for the removal of water (dehydrating 

 agents) and those intended for the removal 



of alcohol (clearing agents). These two 

 groups are recorded under S 10 and S 20 

 below. For the past decade, however, a 

 number of reagents have been recom- 

 mended which may be used either for 

 dehydration or clearing. These, which are 

 given under S 30 below, are referred to as 

 universal solvents for the reason that they 

 are miscible with water and with resinous 

 mounting media and with wax embedding 

 media. 



S 10 Dehydrating Agents 



The function of a dehydrating agent as 

 the name indicates is to extract water 

 from the tissues in order that some other 

 solvent not miscible with water may be 

 substituted. Ethanol is the solvent most 

 commonly used in making microscope 

 slides and is referred to throughout the 

 present work either as abs. ale. or 95% 

 ale., as the case may be. Where ale. or 

 alcohol is referred to without qualification 



the ordinary 95% alcohol (190 proof al- 

 cohol) of commerce is intended. 



Most good dehydrating agents are 

 naturally hygroscopic and should there- 

 fore always be stored over some dehydrat- 

 ing agent which will remove from them 

 the water that they absorb from the air. 

 Weight for weight there is no dehydrating 

 agent as efficient as anhydrous sodium 

 sulfate, but the solubility of this in some 



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