218 FIRESIDE SCIENCE. 



sufficient to make a good-sized pen-knife blade, but 

 no useful implement of a larger size. There is one 

 important element associated with iron in the blood, 

 which does not appear in the " analysis," and that 

 is manganese. This element has not been recog- 

 nized until a comparatively recent date, and its 

 importance has been strangely overlooked. 



Probably no fact in medical or chemical science 

 is more widely understood than that there is " iron 

 in the blood." As a fact it is no more remarkable 

 than that this fluid holds potassium or sodium, or 

 that the brain is permeated with phosphorus. The 

 popular curiosity and interest regarding iron as it 

 exists in the circulation have been excited by the 

 venders of quack remedies alleged to contain some 

 combination of the element. While there is much 

 that is very absurd in the statements popularly pre- 

 sented, it is impossible to overlook the importance 

 co the well-being of the individual of the few grains 

 of iron found in the blood. If the quantity is 

 diminished from any cause, the whole economy 

 suffers serious derangement. We have reason to 

 believe that when the normal quantity (about 100 

 grains) is reduced 10 per cent, the system is sen- 

 sibly affected, and the health suffers. How sensi- 

 tive to all the chemical reactions going on within 

 and around, is this complex machine which we call 

 the body I 



