Inorganic Constituents of Plants. 50S 



pliates found in an ash will, however, to some extent, be de- 

 pendent on the management of the preparation of the ash. If a 

 strong heat, with free access of air, be permitted, part if not all 

 of the sulphur contained in nitrogenized vegetable substances 

 will be converted into sulphuric acid during the ignition. On 

 the other hand, however, if the ash has not been heated suf- 

 ficiently long with free access of air, the addition of an acid 

 to a portion of it will cause the evolution of a not inconsider- 

 able quantity of sulphuretted hydrogen, the source of which has 

 been the deoxidized sulphates. In such a case, if it be wished 

 to make a quantitative analysis of the ash, it must be heated 

 with free access of air until the sulphurets are fully oxidated. 



The carbonic acid, and the charcoal found in the ashes of 

 most vegetable substances (with the exception of some seeds), 

 are always to be viewed as accidental constituents, having their 

 origin in the operation of combustion ; their quantity also is 

 dependent both upon the (juantity and quality of the bases 

 present, and upon the degree of heat which has been employed. 



We now submit to view a list of the inorganic compounds 

 or bodies which have hitherto been found in the normal ashes 

 of vegetables. They are as follow : — 



Acids or bodies 

 Bases. \vhich replace them. 



Potash. Silicic acid. 



Soda, Phosphoric acid. 



Lime. Sulphuric acid. 



Magnesia. Carbonic acid. 



Peroxide of iron. Chlorine. 



Oxide of manganese. Iodine. 



Alumina. ? Bromine. 



Fluorine*. 

 With the exception of iodine, bromine, fluorine and oxide 



* It has long been known that marine plants, and consequently tlieir 

 ashes also, contain iodine and bromine. In some the quantity of iodine 

 is so considerable, that they are had recourse to in commerce for the pro- 

 duction of that element, as in Scotland, for example. 'J'he existence of 

 fluorine in some vegetable ashes, although extremely probable, has not 

 been proved until recently. Careful experiments, conducted under my own 

 superintendence, by Messrs. James, Miiller and lilake severally, have shown 

 that the ashes of French barley, grown in Switzerland, contain very distinct 

 traces of it; both straw and grain were employed. The presence of silica 

 in considerable quantity renders the detection of fluorine very difficult. 

 The process followed was that of H. Rose, which consists in fusing the ash 

 with carbonated alkali, dissolving in water, neutralizing with hydrochloric 

 acid, in a platinum capsule, adding ammonia in excess, after expelling the 

 carbonic acid by evaporation, and precipitating the filtered solution by 

 means of chloride of calcium. In this experiment not less than 10 to 12 

 granmies of ash should be employed. Fluorine occurs in the teeth and 

 bones of animals, having been derived by them from vegetable food; it will 

 doubtless therefore exist still more abundantly in the ashes of plants : it 



