p. B. Wilson — Silica of grasses and other plants. 



silicates ; by Prof. P. B. Wilson. 



My attention was called, some time since, in the examination 

 of the ash of plants obtained by slow incineration in a platinum 

 crucible, to the fact that when the ash is treated with dilute 

 acid, and evaporated to dryness on the water bath, it does not 

 pass into the gelatinous condition prior to complete decomposi- 

 tion o\' the htjdrated mass, as is the case with the silicates soluble 

 in acid, or those decomposed with sodium and potassium carbo- 

 nates. If, however, the ash, prior to the treatment with acid, is 

 subjected to a high temperature, a combination of silicic acid 

 with the alkalies, the alkaline earths, and the earths takes place, 

 if all are present ; then the silica separates in the gelatinous 

 form and presents all of the chemical reactions of silicic acid 

 obtained from the natural silicates. The silica obtained from 

 ash by either of the processes indicated, on close examination, 

 was observed to be entirely free from any combination, show- 

 ing that it had been assimilated in the free state. 



To demonstrate this theory, my friend G-. I. Popplein, Esq., of 

 this city, suggested the application of infusorial earth of the 

 Kichmond formation — found in large quantities on the western 

 shore of the Chesapeake bay — to land sown in wheat. I have 

 obtained straw from wheat so grown, and have found, after it 

 has been treated with nitric acid, and the siliceous remains 

 placed on the field of the microscope, that it consisted wholly of 

 the siliceous shields of Diatomaceae, the same as found i 



scenting that the larger discs in their perfe^ 

 {Actim ' '" ' ■■ ^ ' ■• 



form were absent {AcUnocyclus A'hrenbergii and Actinoptychus 

 undulatus). My conclusions are that they, and there probably 

 may be other forms, are too large to enter the root capillaries. 

 During the corning summer I will attempt if possible to make 

 micrometer measurements of both. 



The discovery of Diatomaceae in their original form in this 

 wheat straw precludes the possibility of the infusorial earth hav- 

 ing undergone any chemical change in the soil, either by forming 

 chemical combination with the alkalies, or the eartjjs, or by suf- 

 fering physical disintegration from any catalytic action of any 

 salts present in the soil 



In the particles of silica placed upon the glass slide, when 

 they were completely separated from each other, the outlines of 

 the individual diatoms were sharply and distinctly detined. On 

 the other hand, when the physical action of ebullition with ni- 

 tric acid was not sufficient for the complete separation of the 



Am. Jour. Sr-i., THrRn ^t.hies-Vou XI, No. 65.-May. 1876. 



