The necessity for the steady supply of phosphorus and lime to the body is the cause of the popularity of Mapes’s superphosphate of lime as a manure.  The farmers who buy it, perhaps, do not know that their bones and other parts are made of it, and that this is the reason they must furnish it to their land; for between the land and the farmer’s bones are two or three other factories that require the same material.  All the farmer knows is, that his grass and his corn grow better for the superphosphate.  But what he has not thought of we will tell you,—­that man finds his phosphate of lime in the milk and meat of the cow, and she finds her supply in the grass and corn, which look to the farmer to see that their stock of this useful mineral compound does not fall short.  Thus in milk and meat and corn, which constitute so large a part of our diet, we have always our phosphate of lime.  There are many other sources whence we can derive it, but these will do for the present.  And thus, when an animal dies and has no further use for his phosphate of lime, it is washed into the soil around, after decomposition of the body has set it free, and goes to make new grass and corn.  Bone-earth (pounded bones) is a common top-dressing for grass-lands.

A small proportion of sulphur is found in flesh and blood.  We prove its presence in the egg by common experience.  An egg—­from which it escapes more easily than from flesh—­discovers its presence by blackening silver, as every housekeeper knows, whose social position is too high for bone egg-spoons or too low for gold ones.  This passion which sulphur entertains for silver is very strong, as every one knows who has ever been under that wholesome discipline which had its weekly recurrence at the delightful institution of Dotheboy’s Hall; and what Anglo-Saxon ever grew up, innocent of that delectable vernal medicine to which we refer?  Has he not found all the silver change in his pocket grow black, suggesting very unpleasant suspicions of bogus coin?  The sulphur, being more than is wanted in the economy of the system, has made its escape through every pore in his skin, and, of course, fraternizes with the silver on its way.  But it was of the sulphur which is natural to the body and always found there that we were speaking.  When the animal dies, and the vital forces give way to chemical affinities, when the phosphorus and the rest take their departure, the sulphur, too, finds itself occupation in new fields of duty.

Chlorine and sodium, two more of the elements of animal structures, produce, in combination, common salt,—­without which our food would be so insipid, that we have the best evidence of its being a necessary article of diet.  The body has many uses for salt.  It is found in the tears, as we are informed by poets, who talk of “briny drops” and “saut, saut tears”; though why there, unless to keep the lachrymal fluid from spoiling, in those persons who bottle up their tears for a long time, we cannot divine.