NO. 1879. PRESERVATION OF OSSEOUS TISSUES— BOETTCHER. 703 



which can not be regarded as a chemical entity, the fact is not estab- 

 hshed. Kerosene, which differs from it only in the lower boiling point, 

 is a recognized household insecticide. The fact that Ascarides and 

 Taenia serrata are not affected by it does not disprove its poisonous 

 qualities. 



Experiments on herbarium specimens show an increase of flexi- 

 bility, obtained by soaking in paraffin. The specimens are less 

 brittle, will stand rougher handhng, do not need to be poisoned and 

 make a better appearance, although they lose their characteristic 

 texture, which is often necessary in their determination. 



WORKING METHODS. 



The methods to be pursued in preserving osteological specimens 

 necessarily vary accordmg to their size, tliickness, and purpose. If 

 the object is merely to prevent cracking during prolonged overland 

 transport, as in the case of tusks in Africa, it may suffice to carefully 

 pour the melted paraffin of 80° to 90° C. into the open end of the tusk 

 previously heated. In employing this process any sudden change of 

 temperature should be avoided. After allowing the tusk to absorb 

 the paraffin for a few minutes, the surplus material should be poured 

 off. The outside of the tusk may then be treated with a benzine solu- 

 tion of paraffin, which should be well rubbed over every part of the 

 surface, using as much as the same will absorb while exposed to the 

 heat of the sun. If this has been well attended to, there is not much 

 danger of longitudinal cracking, so undesirable in ivory intended for 

 miniature painting, although it must be remembered at the same 

 time the slow desiccation and gradual contraction are not checked 

 altogether because of the tendency of the paraffin to liquify more or 

 less in the heat of the sun during the day and to recrystallize as the 

 temperature declines. This method will prove very satisfactory for 

 tusks intended for industrial purposes, as it is undesirable to have 

 the paraffin penetrate deeply. 



If the purpose in view is permanent preservation, a large boiler of 

 a sufficient size to aUow the object to be immersed completely is heated 

 in a water bath. In this boiler the object to be preserved is sus- 

 pended by a wire from an hour or two for small skulls, such as those 

 of rats and mice, to a week or more for tusks of a hippotamus. The 

 heat in the experiments here described was turned on at 9 o'clock in 

 the morning and turned off at half past 4 in the afternoon, and this 

 alternation of heat and cold, in my opinion, proved beneficial, though 

 at present I am not prepared to prove it. 



To allow bubbles of air to escape from cul-de-sac hollows in the 

 skulls, they were frequently shifted to different positions. When 

 fully saturated, that is, when after long observation no more bub- 



