'I he primary rucks contain an almo-t euual proportion of potassium 

 and -odium. l>ut in sea water the compounds ot the latter metal pre 

 iloininate. It may 1>e a-ked, what hecame of the compounds of potas- 

 sium in t!n- di-inte^ration of tin- primary rock>. if so -mall a quantity 

 \vi-nl - M tin- sea water ; They remained \\ it li the other products of the 

 docomjMoitii.ii < if the jirimarv rock-. \Vhen granite or any other 

 similar rock formation is di-int Dialed, tin-re are formed, lie.-ide.- the 

 soluble distance- -and ;md tinel v-divided 



clav, co . .\ '. alumina, and silica. 'I his clav i- carrie<l awav 



li\" th<- water, and i - then depo-u'd in - ' ra t a . It. and esj)eciallv 

 it.- a i ii i\ ui'e \\iih v<'u ' ; i ;;:i!!-. 1'e'ain coi n pounds of jiotaium 



in a u'l'c tlian tho^e of sodium. Tlii- ha- hccii jiro\'ed. 



' ; ' ' .* ; '. If a dilute solution of a |)ota--ium comjiound lie 

 '_''! common nmuld u-ed for Lfrowinu' jilant^. and coii- 

 : -. and the remains oi \t-e;etah!e olecoinjtosit ion, it \\'ill l>e 

 t nd to have retained a :-omewlial consideralile percentage of the 

 mpoMiuK. It' a -:; ! ' ' >t' potassium \- taken, then dunni;' 

 the ti 1 1 ;vi I ion an e pu \ a lent juant it v of a salt of calcium which is a No 

 found, as a rule, in soils i- -el free. Such a process of filtration 

 through 1'melv-divided earth\' substances pi-oceods in nature, and the 

 compound- of poia-siiim are e\'erv\\ here retained 1\ the frialile can h 

 in con-idei'ahlo (juantitv. 'I hi- explains the jire-ence ot -o small an 

 amount of poia--ium salts in the water of rivers, lakes, streams, and 

 oceans, w lie re the 1 1 me and -oda ha \ e accumulated. 'I IM- compounds of 

 potas-ium retained li\- i he frialile ma-s of the earth are ahsorUed as an 

 aijueous solution l.v the root- of />/>i//f*. Plants, as e\erv one kno\\'s, 

 \\h<-n liui'iit l'-a\e an a-h. aiid this ash. l)C.sides various other siihst ancos, 

 without e.xcepiiii ins coi 1 1 j M )ii i ids of potas-ium. Many land 



plants contain a very small amount of -odium compounds.' 1 whil-t 

 j iota -sium and :' compounds ncciii 1 in all kinds ot \'ei;'etah|e a-h. 

 AIIIOIIL;' the 'j.'i.i ra 1 1 \ ciilti\"ated plants, u'l'a-s. pot a toe.-, the turnip, 

 and liiickwheai are part icn larl\' rich in pota-.-mm compounds. 'I he 

 a-h of plant-, and e-peciallv of herhaceous plants. lmrk\\heat Straw, 

 iintlowcr and potato lea\e.- are u-ed in jiractice for the extraction of 

 pot a --i II in coi 1 1 poll I ids. 'I'll ere is Ho dold t that pot a;-.-] ll In <icc ui's III the 

 plant-: them el\e- in the t'oi'in >]' complex compounds, and otten as sails 

 of organic arid-. In certain ca-e- Mich salts of potas-ium are even 

 ex t racier) from the juice of p|:i ni -. 'I'h ii . . or re] and or"//* for exam jile, 

 con i a in in their juice t lie arid oxalat e of potassium, (.V, II K< ),, which is 



