96 VEGETABLE SUBSTANCES. 



LIME SALTS 



Occur partly as invisible, amorphous incrusting 

 substances in the cell-wall, and can then be de- 

 tected in the ashes. Sometimes they occur as 

 well-developed crystals, which are found in the 

 wall itself and elsewhere. 1 



Micro-chemical investigations show that calcium 

 occurs in the cell in the form of carbonate, oxalate, 

 phosphate, and sulphate : 



a. The compounds with carbonic acid are dis- 

 solved by dilute acids with violent effervescence. 

 If the solution has been effected by sulphuric 

 acid, gypsum needles crystallize out in the fluid 

 as in the case of other salts of lime. 



(Cystoliths ; Corallina, Melobesia, Chara, etc.) 



b. Oxalate of lime, the most widely-distributed 

 of these compounds, is not dissolved by potassic 

 hydrate or acetic acid, but it is soluble in hydro- 

 chloric acid without effervescence. 



(It occurs as an incrusting material in the hairs 

 of Asclepias, 2 and in raphides, free crystals, 

 Rosanoff's crystal glands, etc.) 



c. Calcium phosphate 3 has recently been shown 

 to occur in plants. It is insoluble in water, alco- 



1 Holzner : Beitr. z. Kenntn. der Pflanzenkrystalle. Zeitschr. f. 

 Mikroskopie, 1877, I., p. 236, where there is a synopsis of the literature. 

 Van der Ploeg: Deoxalsure Kalk in de Planten, Leiden, 1879. 



2 Kabsch : Bot. Zeitung, 1863. 



3 Nobbe, Hanlein, and Councler : Landwirtsch. Versuchsstationen, Bd. 

 XXIII., p. 471 (Robinia Pseudacacia and Soya hispida). 



