PH O
PHO
( 220 )
gredients. For this purpofe faturate the acidliquor (arifing from the decompofition of bone-afli by lulphuric acid) with pure ammonia,■which will feparate the phofphat and fulphatof lime, and the clear liquor contains the purephofphat of ammonia, if no excels of fulphuricacid has been employed. If carbonat of am-monia inftead of pure ammonia be ufed, fomeof the phofphat of lime remains in folution,which however may be got rid of by evaporat-ing the clear liquor nearly to drynefs, andrediflblving in cold water. The filtered folutionmull then be fuperfaturated with ammoniacarbonated or pure, and gently evaporated tothe cryltallizing point.
The form of this fait is a four-fided prifmterminated pyramidally. When the alkali isnot in excefs it runs into fmall indeterminateneedles. The talte is {harp and cooling.
This fait diffolves in four parts of cold waterand in fomewhat lefs of boiling, but not fomuch as to cryftallize by Ample cooling withoutfurther evaporation.
When heated, it melts, lofes firft its waterwith a portion of its alkali, and then the reft ofthe ammonia flies off, and nothing but purephofphoric acid is left. Hence it is that this isthe only one of the phofphats from whichpliofphorus can he procured, as in fa£t, afterit is red-hot, it is Amply phofphoric acid.
The fulphuric, nitric, and muriatic acidsxlecompofe this fait entirely.
Phofphat of ammonia is ufed confiderably asa flux for earths and oxyds, efpeciaily in ex-periments with the blow-pipe. It becomes inthefe cafes only a convenient mode of apply-ing phofphoric acid, as the alkali is totallyexpelled.
Phosi>hat of Soda and Ammonia. Micro-.eofmic fait, or Fufible fait of Urine .
. When any liquid containing phofphoric acid,foda and ammonia (fitch as urine is) is evapo-rated and its faline contents obtained by cryf-tallization, thefe two phofphats, or a portion of•one or other of them, unite in a triple fait,which is the one in queftion, It will be furthernoticed under the article Urine , whence it wasat firft obtained, but feme of its properties,maybe mentioned in this place.
It feems to have no very uniform proportionsof ingredients, for as Fourcroy obferves, thequantity of ammonia is conftantly diminifhingby fucceffive folutions and crystallizations, and■.the acid to which it was united remains, ren-dering therefore the remaining fait more and
more acidulous; and by long expofure to theair the whole ammonia is loft. This laltwhen firft prepared has an excefs of acid foas to turn fyrup of violets green. It efflorefeesin the air. Diftilied per fe it gives an ammo-niacal water, and a little phofphat of ammoniaalfo riles. Fourcroy eftimates the proportionsin ico parts of this fait to be as follows: viz.of phofphoric acid 32; of foda 24; of ammonia19; of water 25.
When any alkaline phofphat is dropped intoa folution of any barytic lalt, a heavy whitepowder fubfides, which is the phofphat ofbarytes. The fame may alfo be prepared bydigelling phofphoric acid with carbonat ofbarytes, or adding this acid to barytic water.
This fait is infoluble in water either hot orcold, and even in phofphoric acid. Thefulphuric, nitric, and muriatic acids decompofeit by Ample elective attradlion.
It is fufible at a high temperature, and whenkept melted off charcoal by the blow-pipe itgives a yellow phofphoric flame.' 1 *
It is not ufed.
This fait may be prepared like the formereither by double decompofition of the earthymuriat or nitrat, or by the dire£I union of theconftituent parts. It is in the form of awhite heavy pov ier, entirely infoluble in water,but it differs from the former fait in beingfoluble in an excefs of phofphoric acid Beforethe blow-pipe on charcoal it melts and gives apurple flame.
It is entirely decompofed by the fulphuricacid, but only partially by the nitric and mu-riatic acids, and an acidulous phofphat offtrontian is left. In this it differs from thephofphat of barytes. It is compofed accordingto Vauquelm oi 48.76 per cent, of ftrontian,and 41.24 of phofphoric acid.
'Phis i? by far the mo ft important of theearthy phofphats, and is that which has beenexamined with the mod attention.
It is found native both as a mineral and asa conftituent part of a number of animal organsand fluids. 'The mineral phofphat of lime isdeferibed under the article Apatit, of whichthere are feveral varieties in the animal king-dom. Phofphat of lime is contained moilcopioufly in Bone , as has been fully detailedunder that article.
It alio forms the afh or earth that remains
'* yau^uelin.j