394 Transactions. — Miscellaneous. 



unaffected by heat, and is one of the best non-conductors of 

 heat or cold known. One end of a piece of it, 2in. long and 

 Jin. square, may be placed in a gas-jet for two hours without 

 sensibly raising the temperature at the other end, whilst a 

 piece of iron of the same size becomes red-hot in half the 

 time. 



2. It is not in the least affected by the most intense cold. 



3. It is unaffected by damp or moisture, never developing 

 the smallest approach to heat-fermentation, never generating 

 any fungoid growth, or taint of any kind. 



4. It is absolutely free from the least tendency to spon- 

 taneous combustion. It cannot even be fused alone by the 

 most intense heat. 



5. Eats will not touch it. 



6. Pumice is extremely light when properly selected and 

 prepared, being about the same weight as charcoal. 



7. It is perfectly clean, more satisfactory to handle than 

 charcoal, and in case of accidental escape from the insulating- 

 walls it does not blacken or soil, like charcoal, the frozen meat, 

 or the bags which contain it. 



8. In case of fire occurring, from any cause, in any one 

 compartment of an iron steamer or ship, if the bulkheads be 

 made double by an additional sheathing of thin iron at the 

 back, and the prepared pumice be filled into the space, then 

 not only do the bulkheads so filled in secure the original 

 objects of strength, and safety from water, but these bulkheads 

 so filled — with very little addition of weight — will prevent 

 absolutely any fire occurring in one compartment from spread- 

 ing through the bulkheads to the next compartments, with 

 the further safeguard of the complete prevention of any heat 

 from the boiler or engine compartments to the insulating- 

 walls of the cooled-chambers, and removing one of the most 

 dangerous elements of combustion from that cause where 

 charcoal is used. 



I have only to add that the use of carefully-selected and 

 prepared pumice as an insulator, in place of charcoal, on all 

 steamers and ships having cooled-chambers, will secure abso- 

 lute and perfect immunity from fires from spontaneous com- 

 bustion, besides rendering a fire on board arising from other 

 causes more manageable by the absence of charcoal, which 

 only adds fuel to the conflagration, whereas the pumice-filled 

 bulkhead, as before described, presents an impenetrable barrier 

 to its progress. 



By the substitution of prepared pumice in steamers, or 

 freezing-works on shore, in place of the charcoal now in use 

 as the insulator, an absolute safeguard will be provided against 

 all fires from spontaneous combustion ; it will remove the un- 

 easv feeling current anion" the better-informed insurance offices 



