BY \. MK\i> EDWARDS. 27 



type that which comes from the islands on the coast of Pent, 

 As it comes into commerce this guano is a moist powder of a 



light iron-rust color, smelling strongly of ammonia, and having 

 scattered throughout its mass Lumps of ammoniaoal salts of a 

 more or less solid consistency. The guano should be thinly 

 spread out upon a stiff piece of paper and exposed to the air, 

 and, preferably, to a moderate heat for several days or even 

 weeks. In this way most of the moisture and much of the am- 

 monia will evaporate, and less acid will be required to clean the 

 guano. It will now have become much lighter in color, and 

 crumble to a dry powder. A tin pan is now about half rilled 

 with a solution of common washing soda in clean filtered water, 

 and placed over some source of heat, as on a stove. The 

 strength of this solution is not a matter of any great moment, 

 and must vary with the guano manipulated. As soon as it 

 begins to boil, the guano is dropped gradually in, a little at a 

 time, while the liquid is stirred with a glass rod or stick of 

 wood. Considerable effervescence takes place, ammonia being 

 given off, and therefore it must be kept continually stirred, and 

 care exercised to prevent its boiling over. After a while it is 

 poured into a plentiful supply of clean water, and washed there- 

 with several times, care being taken to permit all of the diatoms 

 to settle. As soon as the wash-water is only slightly colored, 

 the guano is transferred to a good sized evaporating dish, and 

 covered with nitric acid, and boiled. While it is boiling, a few 

 crystals of bichromate of potash are dropped in, and the mate- 

 rial washed as in the case of muds. Thereafter the diatoms 

 are boiled in sulphuric acid with bichromate of potash and 

 hydrochloric acid, as before described. 



rhosphatic guanos, as that from Brazil, are somewhat more 

 difficult to treat. They are generally drier than the ammonia- 

 oal kind, and must be boiled in a large quantity of hydrochloric 

 acid as many as three times, and the acid must be poured off 

 while still hot. Thereafter nitric acid and sulphuric acid ami 

 bichromate of potash musl be employed, as in the other Oaf 



3 dimentary Deposits. For the most part these are 

 pulverulent, and easy to clean. Borne, aa found in nature, are 



so pure that they require no cleaning except washing in clean 

 water. Burning on a plate of platinum or mica will often 



