FIXING AND PRESERVATIVE MEDIUMS 63 



water." Fresh-water gastropods are, says Dall, quoting Professor 

 Jno. Ryder {Bulletin U.S.A., No. 39, p. 43), caused to die 

 extended in the same manner, and hardened in alcohol of 

 increasing strengths. 



Turpentine. — Although turpentine is of little or no value as 

 a preservative if used alone, yet it is a powerful insecticide, and 

 may be used with advantage to kill the larvae of moths and 

 beetles in all skins, and even to clean others ; but its greasi- 

 ness is such that, after it has done its work — and half an hour 

 would suffice for this, — it must be removed from the specimen 

 by the benzoline and plaster treatment (see p. 168). 



Benzoline. — This most useful liquid is, needless to say, 

 to be treated with care, and not brought too near to gas 

 or fire-flame. In addition to its almost priceless value as a 

 cleanser of nearly everything, it will preserve beetles for a 

 considerable time — certainly a year — by immersion, and will 

 also readily free them from grease. Moths and butterflies it 

 also frees from grease, kills mites upon them, and only in very 

 rare instances spoils them — some delicate greens and blues 

 being affected. 



What is, perhaps, of equal importance, is its property of 

 preserving animal tissue for a certain time, and birds may be 

 kept for a month in benzoline, and frogs have been kept for 

 several months without much deterioration. As a means of 

 preserving such objects for a short time, until the taxidermist 

 can take them out to be skinned and set up, it has advantages 

 over spirit in its clearness, cheapness, and the facility with 

 which it is procured in out-of-the-way places. It is, of course, 

 more dangerous in bulk, if kept at all exposed, than ordinary 

 spirits ; but if a proper vessel is provided, such as those used for 

 the latter at biological stations, there is no more danger than 

 attaches to keeping a few gallons in a can for ordinary purposes. 



It is of great value as an insecticide, especially in positions 



