58 Transactions of the 



the vegetable kingdom as the ultimate source of the elements of 

 our bodies. If, then, we are constantly removing the phosphorus in 

 the form of phosphates from the soil by means of plants, we must 

 necessarily in course of time exhaust the powers of our fields, 

 unless we return to them the constituents we have taken away. 

 This we are enabled to do by means of superphosphate or bone- 

 manure. Not that this is the only source from which phosphorus 

 is obtainable ; several others offer themselves to us. 



In Bohemia, and more especially in the province of Estre- 

 madura, in Spain, a mineral called apatite, consisting principally 

 of phosphate of lime, occurs in large quantities, and might be 

 made a source of immense wealth to those countries if properly 

 developed. The same mineral is found in small quantities in Corn- 

 wall and Devon. Phosphate of lime abounds also in the bodies 

 called coprolites, which are generally regarded as the dung of 

 fossil animals. They are found in large quantities in the Lias 

 formation in England. Phosphorus thus affords a very good 

 illustration of the circulation of matter, or, as it is often called, the 

 indestructibility of matter. Taken up from the mineral world by 

 the plant ; from that it goes to form part of the animal, and from 

 the animal back again to the mineral world. And so it is with 

 every other substance : nothing is ever lost in the economy of 

 nature ; it merely alters its place or condition, running on in one 

 unceasing round from age to age. The identical atom of phos- 

 phate of lime which once formed part of the system of some huge 

 saurian of the antediluvian world, may now form part of our own 

 bodies, and centuries hence may again contribute its share to the 

 formation of living beings like ourselves. 



The blood does not find so many applications as the bone ; but 

 it is not wasted. I do not know whether it is ever used as the 

 blood of bullocks is in clarifying sugar. The use of animal char- 

 coal in the process of sugar-refining has been already mentioned ; 

 but before the charcoal is applied, blood is added to the sugar, 

 and the mixture is then heated sufiiciently high to coagulate the 

 albumen of the blood. This entangles the coarser impurities, 

 which are then skimmed off". The coagulation of the albumen by 

 heat is exactly the same thing that takes place in boiling an egg. 

 The white of the egg consists of albumen, which, as any one knows, 

 sets into a firm mass when exposed to the temperature of boiling 

 water. 



The principal part of the blood, however, is handed over to the 

 manufacturer of prussiate of potash, the substance which with 

 a certain admixture of an iron salt forms Prussian blue, and is 

 the base of the blue colours with which our clothes and other 

 articles are dyed. There are two prussiates, called, from their 



