Firth. — On the Causes of Fires on Ships. 393 



along the line, to be followed by an avoidance by passengers 

 of all steamers carrying frozen meat. Nor will the matter 

 end there, for in these days every passenger-steamer is pro- 

 vided with a charcoal-insulated chamber to carry its fresh pro- 

 visions for use on the voyage. 



It may therefore as well be remembered that it is by no 

 means beyond the limits of probability that it may be the 

 fate, sooner of later, of many or most ships and steamers 

 carrying frozen meat or other articles in cooled-chambers in- 

 sulated with charcoal to be burned at sea, if this highly dan- 

 gerous material continues to be used for insulating purposes. 



Gunpowder, which will not ignite except by a spark or 

 light, is surrounded by precautions ; yet, notwithstanding the 

 accumulation of scientific opinions and experiments, and the 

 occurrence of many actual fires demonstrating the liability of 

 charcoal to spontaneous combustion, steamers and property 

 aggregating more than a hundred millions sterling in value, 

 together with tens of thousands of seamen and passengers, are 

 every year sent to sea, carrying along with them charcoal, a 

 material far more dangerous than gunpowder — so full, indeed, 

 of the elements of catastrophe that public opinion is not 

 likely to tolerate such a condition of things much longer. 



It is evident, therefore, that the use of charcoal as an in- 

 sulator is full of danger to all parties — steamship-owners, 

 freezing- and dairy-works proprietors, insurance companies, 

 and sea-going people generally. The dangers incidental to 

 the sea are serious enough without increasing them in an 

 unnecessary manner by sending ships to sea with such a dan- 

 gerous article as charcoal on board. 



Unless a safe substitute for charcoal be available, then 

 great losses of life, of shipping, and other property, followed 

 by much higher insurance-rates, lower prices for sheep or 

 higher prices of meat to consumers, are looming in the not very 

 distant future. 



I should not have undertaken an investigation so arduous 

 and unsatisfactory unless I had believed in the existence of a 

 material as a safe and perfect substitute for charcoal, for he is 

 but an indifferent doctor who tells you that you are suffering 

 from a disease, but fails to point out a remedy. 



For many years I have been acquainted with the peculiar 

 properties of pumice, a product of New Zealand and of two or 

 three other countries. In the course of my investigations I 

 have made many careful experiments, with the result that I 

 have ascertained that amongst the several kinds of pumice 

 one or two varieties are suitable in the highest degree, wdien 

 properly prepared, as a safe and perfect substitute for charcoal 

 for insulating purposes, for the following reasons : — 



1. Pumice, properly selected and prepared, is altogether 



