EXPLOSIBILITY OF COAL OILS. 



By T. ALLEN, 



PROVIDENCE, RHODE ISLAND. 



So recent has been the introduction of coal oil into general use for 

 burning in lamps, that few persons have as yet had satisfactory oppor- 

 tunities of obtaining a knowledge either of its peculiar properties or 

 of the peculiar processes lately invented for extracting oil from coal 

 in quantities sufScient to constitute a new and important article of 

 commerce. 



Some of the qualities of coal oil sold in the market having proved 

 dangerously explosive, the directors of fire insurance companies have 

 become alarmed, and have increased the rates of fire insurance on 

 property where such oil is stored or burnt in lamps, deeming it to be 

 extra hazardous, like camphene and "burning fluid." But a manifest 

 difi'erence being discoverable in the inflammability of the oils sup- 

 plied from different establishments, it is evident that some mode of 

 distinguishing the safe from the unsafe oils has finally become indis- 

 pensable for the security of the insurers as well as for the satisfaction 

 of the insured. Accordingly, in compliance with a request of the 

 board of directors of the Rhode Island Mutual Fire Insurance Com- 

 pany, the following investigations have been made to determine, by 

 practical experiments, the Comparative explosibility of coal oils, and 

 the consequent probable danger of the use of them in lamps for 

 lighting manufactories and dwellings. 



Several of the experiments may appear to be very simple; but as 

 they serve to exhibit instructive facts for popular information, they 

 are none the less valuable for dispelling unfounded fears of danger, 

 and for inducing due caution where there may exist causes for alarm. 



All the liquid products of the distillation of coal are popularly con- 

 sidered as "coal oils;" but there is an extraordinary difi'erence in 

 their volatility and inflammability, from the explosive flash of volatile 

 spirits, resembling ether and alcohol, to the dull heavy blaze of a 

 smoking tar. The several peculiar qualities of the products of the dis- 

 tillation of bituminous coal will be most readily learned from a de- 

 scription of the processes j)ractically adopted by the distillers for 

 obtaining them. 



The process of making common coal gas by the distillation of bit- 

 uminous coal in red-hot iron retorts or ovens, set over furnaces, is well 

 known; but it may not be generally known that before the iron 

 retorts become heated red-hot, a tarry liquid or oil first comes over 

 into the main gas-pipes, and is collected in a separate cistern. This 

 dark liquid has an exceedingly strong and disagreeable odor, and the 

 only use of it at first was that of making coal tar. A nearly similar 



