The four elements already referred to are by no means all the material ingredients of animal bodies. There are, also, phosphorus, lime, magnesia, soda, sulphur, chlorine, and iron; and if you believe some chemists, there is hardly a mineral in common use that may not be found in the human body. We doubt, however, whether lead, arsenic, and silver are there, without the intervention of the doctor. What becomes of the phosphorus and the rest, when an animal dies? Oh, they take up new business, too. They are as indispensable to the animal frame as the four most prominent ingredients. We eat a great deal of bread and meat, and a little salt,--but the little salt is as important to continued life as the large bread. There is hardly a tissue in the body from which phosphorus, in combination with lime, is absent; so that the composition of lucifer-matches is by no means the most important use of this element. The luminous appearance which some putrefying substances, particularly fish, present at night, is due to the slow combustion of phosphorus which takes place as this element escapes into the air from the decomposing tissues. 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.