13 
caps. Boxes or tins with loose lids should be avoided, as the powders are 
apt to sift out into the other luggage. Arsenical soap may be kept in a 
paste jar with two compartments — the soap in one compartment and a 
small brush in the other in which water may be placed when needed for 
use and poured out when finished. A very convenient method on packing 
trips is to carry the powders in double paraffined bags, made by putting 
one bag inside another bag. When in use, the tops of the bags may be 
rolled back to scoop the powder out, or the specimen may be dipped into 
the bag. 
As some persons are peculiarly susceptible to local irritation of the 
skin when handling arsenical preparations, particularly when arsenic is 
used in quantity for long periods, various non-poisonous mixtures are 
coming into common use by collectors. These non-poisonous compounds 
preserve the specimens effectually from decay, but are less effective than 
arsenic in keeping insect pests away. As all specimens are unsafe from 
attacks of moths, dermestes, etc., except in far northern regions, unless stored 
in insect-proof cases, this disability is perhaps more apparent than real. The 
use of arsenic is not strictly necessary when a collector is working for a 
properly equipped museum where the specimens can be placed in insect- 
proof cases within a reasonable time. If fumigated on entrance such speci- 
mens will keep indefinitely without the use of poisonous preservatives. 
Some authorities do not consider arsenic a sure preservative against insect 
pests, but where arsenic-treated skins have spoiled the cause is usually 
imperfect and inadequate poisoning, particularly around the terminal bones 
of wings, feet, and beak of birds, and the toes of mammals. The writer 
has stored skins that were preserved with straight white arsenic in a 
case with large cracks open to moths and dermestes (bacon-beetles) for 
25 years, and taken them out uninjured by insect pests, whereas other 
skins in the same case had been riddled by insect larvae. The moral seems 
to be that collectors who do not have proper air-tight cases for permanent 
storage should use arsenic thoroughly, and plenty of it, in preserving their 
specimens. If used with ordinary care, arsenic offers no danger to the 
health of the collector unless he is constitutionally susceptible to its effects. 
Dr. Glover M. Allen, of the Museum of Camparative Zoology, Harvard 
University, recommends the use of a mixture of sixteen parts saltpetre 
(potassium nitrate, KNO 3 ) to one part of alum as a preservative instead 
of arsenic. Some of the field collectors for the same museum have used 
this mixture with success in many lands. It seems to set the hair, does 
not liquefy in damp weather as salt does, and has the advantage of being 
non-poisonous. 
Mr, Colin C. Sanborn informs the writer that the Field Museum of 
Natural History, Chicago, uses borax mixed with naphthaline crystals 
(Ci 0 H 18 ) for preserving both mammal and bird skins, and the mixture has 
proved to be satisfactory on several extended field trips to South America. 
The borax and naphthaline mixture has also been used with good results by 
some of the collectors for the National Museum of Canada. The borax 
forms an effective preservative and has the advantage of dissolving readily 
if the skin has to be relaxed later. The naphthaline discourages blowflies 
from attacking skins that are drying, and probably repels mould and insect 
pests to some extent while the specimens are in transit from the field to the 
