INORGANIC SUBSTANCES. 99 



ash occurred in the organic substance. Thus, to take a simple example, nothing 

 can be certainly made out from it with regard to the presence of lactic acid, 

 since all the lactates are reduced by incineration to carbonates; so again, from 

 the presence of sulphates and phosphates in the ash, it cannot be determined 

 whether the sulphuric and phosphoric acids pre-existed as such in the organic 

 substance, or whether they were present as sulphur and phosphorus, which, hav- 

 ing become oxidized during the incineration, have combined with alkaline or 

 earthy bases previously combined with lactic or carbonic acid. Further, the 

 carbon of the organic compound may produce important alterations, during its 

 combustion, in the condition of the mineral salts \ thus it will tend to reduce 

 the sulphates to the condition of metallic sulphurets, and to volatilize a portion 

 of the sulphur in the condition of sulphurous acid ; and it will have a similar 

 effect upon the phosphoric acid of the acid salts. So, again, common phosphate 

 of soda, at a high temperature, removes a part of the base, not only from the 

 carbonates but also from the sulphates of the alkalies, as well as from the me- 

 tallic chlorides of the ash; so that not only does all the alkaline carbonate dis- 

 appear from the ash, but a portion of the hydrochloric or sulphuric acid may 

 also be lost. When we consider these and other facts in reference to the analy- 

 sis of the ash, we shall readily accord with Prof. Lehmann's remark, " that 

 most of these analyses should be used with great caution, and that physiological 

 conclusions should not be too readily drawn from them." The new methods 

 recently introduced by Prof. H. Hose have led that eminent analyst to the con- 

 clusion, that various compounds of potassium, sodium, calcium, iron, phospho- 

 rus, and sulphur exist preformed in organic substances in an unoxidized state, 

 and take an important part in their metamorphoses ; for he finds that in the 

 carbonaceous residue left after the incineration of an animal or vegetable sub- 

 stance, there is always a certain quantity of alkaline and earthy salts which can- 

 not be removed from it by the ordinary menstrua, and which must, therefore, 

 exist in it in some peculiar state of combination. And it is a confirmation of 

 this view, that the proportion of such mineral matters contained in blood, flesh, 

 milk, and yolk-of-egg, amounts to as much as from one-third to one-half of the 

 whole ; whilst those of urine, in which there is independent reason to believe 

 that nearly all the bases and radicals are oxidized, do not amount to 0.6 per 

 cent. 



73. In the following account of the mineral components of the body, there- 

 fore, those only will be mentioned, whose presence in it has been clearly deter- 

 mined ; and even these must be arranged in two categories, according as their 

 presence is essential or accidental. For whilst there are certain substances, 

 which are constantly met with in such large amount, and which so obviously 

 fulfil important purposes in the economy, that they may be unhesitatingly 

 ranked among the essential components of the body, there are others, which, 

 although very commonly present, are found in very small proportion, and under 

 circumstances which lead to the belief that they neither take a share in the 

 nutritive operations, nor discharge any mechanical function in the living body, 

 but that they have been (so to speak) accidentally introduced from the food, 

 and that they are retained merely through defect of the eliminating processes. 

 The presence of such matters, therefore, is of comparatively little interest to 

 the Physiologist ; but it is of great importance to the Medical Jurist, who may 

 be called upon to declare whether copper, lead, or arsenic, found in a dead 

 body, can be justly regarded as a normal component of the tissues. We shall 

 first consider, then, those inorganic substances which are to be regarded as essen- 

 tial components of the Human fabric ; and since no classification of them, in 

 the present state of our knowledge, would be likely to have any permanent 

 scientific value, we shall arrange them in the order of what appears to be their 

 relative importance in the economy. From these we shall pass to the sub- 



