280 Annual Report of the Consulting Chemist. 



A larger number of artificial manures, belonging to the class 

 of phosphatic manures represented by superphosphate, were 

 analysed in 1873 than in any preceding year ; and most were 

 found of good quality and worth the money at which they were 

 sold. 



Dissolved bones are held deservedly in high repute by farmers. 

 Unfortunately genuine dissolved bones, that is, a manure con- 

 sisting entirely of bone-dust, treated with sulphuric acid, cannot 

 be prepared in sufficient quantity to meet the demand, on 

 account of the scarcity of bones ; and, in consequence, the term 

 " dissolved bone " is now frequently applied by manure-dealers 

 to mixtures of mineral superphosphates with small quantities of 

 bone-dust. 



Dissolved bone as sold at present rarely contains more than 

 20 per cent, of bone-dust, and often as little as 10 or 12 per cent. 

 On account of the difficulty of procuring genuine dissolved bones, 

 some farmers are in the habit of buying separately bone-dust and 

 oil of vitriol, and of preparing dissolved bones themselves. If 

 bone-dust can be bought in a particular locality at an ex- 

 ceptionally low price, and the acid necessary to dissolve it is 

 obtainable at a moderate cost of carriage, the practice of pre- 

 paring dissolved bones at home is no doubt commendable ; but, 

 generally speaking, the railway charges for the conveyance of 

 oil of vitriol in glass carboys is so' great, that the home manu- 

 facture of dissolved bones entails an expense which a manure 

 manufacturer who makes his own acid has not to incur. More- 

 over, soluble phosphate of lime is much more economically 

 obtained from coprolites, Spanish phosphorite, and ' a great 

 variety of other phosphatic minerals than from bone-dust ; and 

 although there is a great difference in the practical value and 

 efficacy of insoluble phosphates occurring in an artificial manure 

 in the form of bone and in the shape of mineral phosphates, 

 soluble phosphate of lime, being a definite chemical compound, 

 is equally valuable from whatever source it may have been 

 obtained. 



It is therefore, as a rule, no advantage to the farmer to make 

 his own dissolved bone-manure. If, however, experience should 

 have taught him that his turnip crops are much benefited by 

 manures which contain more or less undissolved bone, the best 

 plan he can pursue of procuring the kind of artificial manure 

 Avhich is specially suited to his requirements, is to buy separately 

 bone-dust and mineral superphosphate of a guaranteed strength 

 a month before the turnip crop is sown, and to proceed as 

 follows : — In the first place the bone-dust should be thoroughly 

 Avetted with water ; if boiling water can be used, so much the 

 better. If the bone-dust is rather dry and impregnated with 



