166 REFRIGERATION AND REFRIGERATOR INSULATION ON BOARD SHIP. 
A few years ago, in a meat market in Seattle, a new refrigerating plant, which had 
what might be called ordinary commercial insulating material, broke down, and before new | 
parts could be obtained to replace the broken ones, and the machinery put in working order 
again, the damage to the meat in the market amounted to more than the cost of the refrig- 
erating plant. 
Therefore, when it comes to efficiency in insulation, there is still room for improve- 
ment. Perfection cannot be attained, but balsa wood will surely help to make insulation per- 
fect, as it is not only a very efficient non-conductor, but has sufficient structural strength, 
and, through its physical properties, permits of constructing units with practically unbroken 
insulated surface walls. 
A small ice-box, or pony refrigerator, made by the Welin Company, is of balsa wood, 
2 inches thick, about 36 inches long, 21 inches wide, and 22 inches deep, and weighs about 
30 pounds. Such a box could not be made up of any other known insulating material. It 
is strong enough to stand severe jars, and a man could jump on it without straining it un- 
duly. Of course, other woods will stand more rough usage than balsa, but, to meet this 
factor of additional strength, particularly on the surface, paneling made from the bark and 
waste of the wood is applied to the outside. 
A small container, on the order of a thermos bottle, but in the form of a box made of 
1-inch material, has a capacity of about 1 cubic foot and weighs 6 pounds. When going on 
an automobile trip or something of that sort, the “lunch” can be placed in such a container— 
whether it is to be kept hot or cold. If it is wanted cold, a little ice should be put in to keep 
it So. 
Butter has been sent all the way from Virginia to Southern California in such boxes, at 
an average outside temperature of 82°, and the trip took eight days by the slowest route. 
Yet, when the boxes arrived at Los Angeles, the butter was still hard and frozen. 
Even if balsa had 30 per cent less efficiency as a non-conductor, the writer believes 
that it would meet a very common requirement for insulation, not satisfied by another ma- 
terial lacking in structural strength, which makes it possible to eliminate all leakage of heat 
through imperfect joints, or by use of cement or nails which may be classified as good con- 
ductors. Other insulating materials are almost entirely limited to use as a lining for a 
structure built of good conducting materials. 
There are a thousand and one uses for balsa, and in the future new ones will contin- 
ually develop. Thanks and grateful acknowledgment are due to Professor Carpenter for the 
earnest scientific work he has done in investigating this wood. 
Mr. Massa (Communicated) :—Referring to Professor Carpenters remarks and the 
samples of balsa wood, this will undoubtedly be an interesting material to experiment with 
further in actual installations and to observe the results as to its durability. 
I note no mention is made of the matter of fire resistance, and I understand that the 
balsa wood is not fire-proof. 
As to fitting the balsa wood in place it is not clear to the writer as to why it should be 
any easier to fit than is cork. 
As to the matter of cracks and joints in cork work being filled with cement, the instruc- 
tions to workmen on this point are uniformly to exercise the greatest care to avoid any 
cement in the joint, and the writer has never happened to see a case where these instruc- 
tions were not followed. It may be, however, that this defect occasionally does occur. 
Further, with reference to the ease of fitting cork in ship-work, an installation was made 
