s CALCAREOUS MANURES-APPENDIX. 



223 



ihe phosphate of lime. Two hundred grains of the triturated earth were snflered to stand 

 (with occasional agitation) in contact with a dilute hydrochloric acid for three hours. 

 The whole was then transferred to a filler, and the eartli well washed theieon, with 

 abundance of tepid water. The clear iluid and wasiiinj^s thus oLtained were super-satu- 

 rated with ammonia, and tlie precipitate subsequently digi^sted in a warm jjotass^c solution 

 for the removal of the silica and the alumina. The per-oxide of iron and phosphate of 

 lime now remaining, after being well wasln-d, were treated with a cold, dilute acetic 

 acid, whereby the pliosphale alone was taken into solulion. It was then piTipilated by 

 ammonia, dried, ignited and weiglied. Having found reason to believe that the propor- 

 tion of finely divided phosphate of lime was pretty uniform in the different specimens 

 of the green-sand, I was only at the pains to determine its exact proportion in speci- 

 men No. 1.* Having ascertained how much peroxide of iron each sample contained, 

 this amount was deducted Irom that yielded by the treatment of tlie same specimen with 

 nitroliydroch.loric acid, (aided by gentle heat,) whex'eby the sulpluiret of iron was de- 

 composed. Thus l!ie exact quantity of iron which was engaged by the suiphUr (and 

 consequently the amount of bi-sulphuret of iron) was ascertained. 



The carbonate of lime was determined in the usual way, viz., by treating thefirst obtained 

 solulion in hydrochloric acid with ammonia, whereby the silica, alumina, peroxide of 

 iion, and phosphate of lime were thrown down, leaving the lime and magnesia alone in 

 a state of su.«pension. The former was precipitated by oxalate of ammonia, and subse- 

 quently the latter by phosphoric acid. 



The sulphate of lime was ascertained by boiling a determinate quantity of the green- 

 sand in water until the whole of this salt present was taken into solution. The clear 

 solution was treated with chloride of barium, and the sulphate of baryta ignited and 

 weighed. The sulphuric acid present in the earth was thus arrived at, and, by subse- 

 quent calculation, the sulphate of lime oiiginally present was ascertained. 



Sulphate of alumina (but no sulphate of iron) was found to exist, in traces, by the 

 precipitation of alumina, occasioned on the treatment of the wafer boiled on the earth 

 with ammonia. But in each case it was too inconsiderable for the determination of its 

 proportion. Chloride of calcium (muriate of lime) was ascertained by treating the 

 same fluid with nitrate of silver. Its proportion did not exceed that in which it exists 

 also in common soils. 



Results obtained on specimens of green-sand earth from Coggins Point, James river. 



'•No. 1. From 8 inches within the exposed side of a ravine, wheie a sirea.Ti flowed 

 by, and 15 feet from the top of the green earth. '"t [Middle part of stratum B, 

 see page 218.] 



Hygrometric moisture, (lost at 300°) - - 5.50 

 By heating to low redness, it lost in addition 2.0-3 

 Phosphate of lirne ..... o.25 

 Carbonate of magnesia, in decided traces. 

 Sulphate of alumina, in traces. 

 "No. 3. Same as number 1, except from a deeper excax^ation. 



Hygrometric moisture (lost at 300°) -_ - 4.600 

 By heating to low redness it lost in addition - 2.200 

 Carbonate of lime - - - - - 1.550 



Bi-sulphur-jt of iron 3.0GG 



Carbonate of magnv'^sia and sulphate of alumina in traces. 

 Phosphate of lime, about as in number 1, 



Sulphate of lime 0.813 



" No. 6. Three feet below the river beach, [from pit, lower par^. of D, hclf a nila 

 distant from preceding.]" 



Hygrometric moisture S.iOO 



By heating to low redness, it lost in addition - 2.CG0 

 Carbonate of lime - - - - - 0.535 



Ei-sulphuretof iron - .... 2060 



Sulphate of lime 0.C61 



Carbonate of magnesia and sulphate of alumina in traces. 

 Phosphate of lime as in number 1. 



* 1 will here observe that, by the process now described, it was ascertained that had 

 the whole of the precipitate by ammonia from the hydrochloric acid solution been taken 

 for phosphate of lime, it would have involved the error of an over estimate of the phos- 

 phate by nearly 800 per cent. 



t This specimen was not thoroughly analyzed, and therefore the contents are reported 

 but in part. The next (No. 3) was deemed the most important, and a more correct speci- 

 men of this layer, (D,) and therefore to it the examination of Prof. Shepard was especially 



