IX. Ohfervatiwjs on the Tranjition of animal or alforbin^ 

 Karth to the State of calcareous Earth *, Bj B. G. Sage^ 

 Director of the frjl School of Mines t 



J. ll£ adbes protluced by burnt bones are white, and com- 

 pofed of more than two-thirds of animal earth, and of a part 

 of that fame earth combined with phofphoric acid. They 

 produce by lixiviation a pretty large quantity of natron, fronv 

 which the fire, according to all appearance^ has feparatcd 

 the phofphoric acid. 



Bone-aflies ought to be confidered as a phofphoric fait 

 ■with an exccfs of animal earth. Thefe aihes, deprived of 

 their natron by lixiviation, are infipid, and infoluble in water ; 

 but the phofphoric fait becomes folublc if it be difengagcd 

 from the excefs of animal earth with which it is combined, 

 and which may be effeAed by means of the vitriolic acid; 

 Fourteen parts of tliis acid concentrated are requifite for 

 twenty-four of bone-afFies : the more they are calcined to 

 whitenels, the larger will be the quantity of vitrifiable phof- 

 phoric acid extrafted from them. It is contained in them 

 in the proportion of a third. This fait, compofed of animal 

 earth and phofphoric acid, may be decompofcd by fixed al- 

 kali, which precipitates from it an mfoluble calcareous 

 phofphorous fait. This charafter of infoluhility ferves to 

 lliovv tliat there is a difference between the animal earth and 

 the calcareous earth, fincc the phofphoric acid fait, with a 

 bale of animal earth, is foluble in water. When vitrified, it 

 produces a pellucid mafs of a light blue tint ; while the phof- 

 phoric fait with a calcareous bafc produces by fufion a femi* 

 traniparent white glafs, cryftallilcd at its furface into a kind 

 of dendrites. 



Six ounces of vitrifiable phofphoric acid fait, dried into a 

 foft palte, required four ounces of fixed alkali of tartar to be 



* Calcareous earth differs frorr. tb.at of bones in being compofed of 

 acidum pingiie and an txctls of Knimal canli. Calcination reduces it to 

 lime : b'jt this is nr.t tiic cafe with the earth of bones, w'!''^'' 's a phof- 

 phoric fait wi^h excefs of animal earth. The name oi ph'.fpbat of llnit). 

 given to the tarth of bones, is confequently iinproj;cr. 



decompofttdM 



