1858. 



NEW ENGLAND FARMER. 



507 



low color. Both are excellent feed for fowls. 

 I can raise almost every kind of garden vegeta- 

 ble upon my ground : the greatest difficulty is in 

 obtaining good seed. That which you sent me a 

 year ago was the best I ever had, scarcely a sin- 

 gle seed failed to germinate. Most of the seeds 

 which we get from California are of the poorest 

 quality, and almost as costly as the gold dug from 

 their sands and rocks. 



Finally, I must tell you that gardening and 

 farming generally, at the Islands, are in rather a 

 primitive state ; it is but recently that much at- 

 tention has been turned in that direction. The 

 soils of different localities, with perhaps one or 

 two exceptions, have never been analyzed, and it 

 is hardly possible to guess what elements are 

 wanting for our different plants and fruits. I have 

 30 or 40 fruit trees from California, mostly peach- 

 es, which grow well, but do not bear, the young 

 fruit dropping soon after the blossom, while the 

 peach from the seed bears well. What is the 

 reason ? The mango is a favorite fruit here, and 

 it grows luxuriantly in rich, warm localities. 

 Most tropical fruits, I doubt not, would do well 

 here, and very many of the fruits and berries of 

 the temperate zone, did we know how to culti- 

 vate them ; as we have every variety of climate, 

 from the torrid level of the sea to the region of 

 frost and snow, upon our magnificent mountains. 

 But let me not be further tedious to you. I wish 

 I had time to write something worthy of a place 

 in your excellent paper, which many of us read 

 with great interest. 



Very truly, J. Fuller. 



For the New England Fanner. 



"IS CHAHCOAL LIABLE TO SPONTANE- 

 OUS COMBUSTION?" 



Mr. Editor : — I quote the caption of a para- 

 graph in your paper of 18th inst., and in com- 

 pliance with your general invitation for some one 

 to investigate the matter, I give you the results 

 of some experiments which I made many years 

 ago, and communicated to the American Acade- 

 my of Arts and Sciences, and to several other 

 scientific associations. 



The theory your article alludes to is probably 

 incorrect, as to moisture setting charcoal on fire. 

 That hypothesis is probably founded upon the 

 idea, that charcoal made at a high temperature is 

 liable to have particles of reduced potassium 

 mingled with it, the potassium coming from the 

 reduction of the potash of the wood. 



Now it is a fact, that charcoal made at low 

 temperatures is most liable to spontaneous com- 

 bustion, or rather ignition at low temperatures. 

 The red-brown charcoal, made from 300 to 600° 

 Fahrenheit, is of this kind, and no reduction of 

 potassium could take place at such temperatures, 

 indeed, it remains to be proved that metallic 

 potassium exists in any charcoal. 



The true theory of ignition of moist charcoal 

 in drying is this. The cells of the coal are filled 

 with water. Heat expels the water as vapor, and 

 the air rushes in and oxygen is rapidly condensed, 

 producing great heat, just as takes place in pla- 

 tinum sponge over the hydrogen jet. Even char- 

 coal, that has not been wet, but has just been made 

 and extinguished, is liable to re-ignite, since the 



extrication of the natural moisture of the wood, 

 and the discharge of light carburetted hydrogen, 

 leaves the cells empty, and air rushes in to supply 

 the vacuum, and condensing gives out much heat. 

 "A fragment of recently burned charcoal, of con- 

 venient size to be introduced under a small air- 

 jar, over the mercurial cistern, will soon take up 

 many times its own volume of air, as will appear 

 by the rise of the mercury in the air-jar. In this 

 case it absorbs more oxygen than nitrogen, the 

 residual air having only eight per cent, of oxy- 

 gen in it." ("Sillinian's Principles of Chemistry, 

 page 219. Phil. Ed., 1852.") The same author 

 observes that recently prepared boxwood charcoal 

 absorbs 9^ times its own bulk of oxygen gas, 

 and 1^ times its bulk of nitrogen. 



I have found that the light porous varieties of 

 charcoal, which has been sa.turated with moisture, 

 were very liable to take fire when dried, even at a 

 temperature somewhat below that of boiling wa- 

 ter, 212*^ Fahrenheit. The greater combustibility 

 of these light spongy charcoals. Is partly owing to 

 their being poor conductors of heat, so that it is 

 not readily dissipated by conduction, and hence 

 the heat rapidly accumulates, as the oxygen con- 

 denses in the pores or cells. 



Many years ago I made my first experiments 

 on this subject, and have since frequently repeat- 

 ed them, or made observations confirming those 

 I had before performed. 



The first experiment was this : I took a piece 

 of wet, porous charcoal from my laboratory cel- 

 lar, and attempted to dry it on the top of a stove- 

 drum, on which had stood and was still there, 

 and at the temperature of the stove, a jar of 

 water. The charcoal was laid close to the water- 

 jar, and received no more heat than that. Soon 

 as the charcoal became dry, it took fire, and yet 

 the water was not boiling hot and had not boiled. 

 The charcoal was so thoroughly on fire that It 

 could not be extinguished by placing it on a cold 

 marble table, but continued to burn until It was 

 reduced to ashes. In this case, the oxygen of 

 the air had penetrated into all the cells of the 

 charcoal, and It was on fire all through. 



The next experiment I made was in Bangor, 

 Me., when giving some lectures on chemistry 

 and geology. 



I had occasion to render some gunpowder and 

 pulverized charcoal very dry, and for this pur- 

 pose spread the gunpowder on the top of a stove- 

 drum, and placed a package of charcoal, done up 

 tightly in a sheet of letter paper on the same 

 stove, on top of the gunpowder. When I thought 

 It dry enough, I took the paper package of char- 

 coal from the stove, and placed It on a table ; on 

 opening the paper, a few minutes afterwards, I 

 found all the charcoal had taken fire. The gun- 

 powder still remained safely on the stove, and 

 the pan of water on it was not boiling hot. 



The first cited experiment I have thrice re- 

 peated with success, employing common pine 

 charcoal, taken from my cellar. 



Hence you see that the precautions taken by 

 your manufacturing friend are well grounded 

 and wise. It would be well If builders, carpen- 

 ters and masons were more fully convinced of the 

 readiness of wood and charcoal produced jat low 

 temperatures to take fire, for then they would be 

 more careful in the arrangement of the wood- 

 work near chimneys and stove-pipes, and would 



