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REFRIGERATION AND REFRIGERATOR INSULATION ON BOARD SHIP. 167 
recently of pure sheet cork on supply ship No. 1, the Bridge. The success of the work 
was largely a matter of proper design. I am sorry that this installation did not occur to 
me in my oral discussion in reply to Mr. Williams’ remarks. 
I want to take this opportunity to add the following notes with regard to Mr. Wil- 
liams’ comments on my paper. 
First, as to ice-tanks and the undesirability of sheet cork as an insulating material at- 
tached directly to the tanks, I am sorry to note that I omitted in my paper one of the prin- 
cipal reasons for avoiding this construction. Not only are ice-tanks, as ordinarily con- 
structed, very rough work as compared with the shell of the ship, but the metal is subjected 
to a very wide range of temperatures, and if the cork is cemented directly to the metal the 
different coefficients of expansion of cork and metal will cause the cork to separate from 
the tank and leave a space in which moisture will accumulate. This same difficulty would 
undoubtedly occur in case cork is cemented directly to the skin of a ship in insulating large 
compartments. In the case of submarines, on the other hand, the range of temperatures 
to which the ship is subjected is much smaller, so that this difficulty does not appear. 
With regard to the maintenance of uniform temperatures in refrigerators with wall 
coils, Mr. Williams’ comment is based on his experience with large compartments and 
goods that are held in them for relatively long periods and at steady temperatures. This 
limitation should have been noted in his remarks. My notes, as already stated, refer to 
small compartments that are subject to rapidly varying conditions, and my statements re- 
garding the effect of this coil arrangement are based on actual installations. 
Coming back again to the question of balsa wood, I have the following quotation to 
submit from a letter by Mr. J. H. Stone :-— 
“Taking up Captain Lundin’s remarks first, he states that the balsa wood is mainly a 
sort of pith with a great affinity for water and he states that all the usual methods of 
waterproofing failed. Finally, according to his statement, a process which he does not de- 
scribe but calls the Marr waterproofing process, proved satisfactory, rendering the wood non- 
absorbable. Before being able to comment on this method it would be necessary to know 
of what it consists, but it is evident that it has not been tried under severe practical condi- 
tions for any considerable number of years, and until that has been done it is impossible for 
anyone to be sure that it will be durable. Its cost must also be taken into consideration. 
“I do not find a word as to the most important question of all, viz., its fire-resisting 
value. I take it for granted, because of the absence of any reference to this point, that as yet 
no satisfactory means has been found of fire-proofing the balsa wood. In these days any 
insulating material, no matter how efficient, must be either fire-proof or very slow burning 
to be favorably considered by practical men, and this is most important in the insulation of 
vessels. 
“There was in England some years ago an uneasy feeling that various refrigerated ships 
that were lost with all on board—none knew how—might have come to their end through 
spontaneous combustion taking place in their powdered charcoal insulation, and the Lon- 
don Board of Trade had experiments made and held an exhaustive inquiry. As I recall it, 
this inquiry resulted in a Scotch verdict “Not Proven,” but charcoal has from that time on 
been gradually abandoned by British shipowners. They have taken to mineral wool which 
they call silicate cotton, and later to cork, using both granulated and sheet cork. I am 
certain that unless this material can come to them and to American shipowners as well, 
