Miscellaneous. 485 



of carbon wore poured into the five fasciculi ; the box was tightly 

 closed, and the whole left for a month (January 15th to February 

 15th). All the insects were destroyed and no injury was done to the 

 specimens or to the papers on which they were fastened. A little 

 later in the season a fortnight was found to be sufficient. The ex- 

 pense of the operation is very small ; and M. Schnetzler recommends 

 that the boxes should be placed under a shed, as in case of the es- 

 cape of any vapour from them there might be danger of explosion. 

 The same process may be employed for collections of insects. — 

 Comptes Rendiis, April 10, 1876, p. 863. 



Silica of Grasses and other Plants carried up as Diatoms or other 

 Siliceous Grains, and not in ■'Solution or as Soluble Silicates. Bv 

 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 eva- 

 porated to dryness on the water-bath, it does not pass into the gela- 

 tinous condition prior to complete decomposition of the hijdrated 

 mass, as is the case with the silicates soluble in acid, or those decom- 

 posed with sodium and potassium carbonates. "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 alkahne earths, 

 and the earths takes place, if all are present ; then the silica sepa- 

 rates in the gelatinous form, and presents all of the chemical re- 

 actions of silicic acid obtained from the natural silicates. The silica 

 obtained from ash by either of the processes indicated, on close ex- 

 amination, was observed to be entirely free from any combination, 

 showing 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 iufusorial earth of the Rich- 

 mond 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 

 niti-ic acid and the siliceous remains placed on the field of the micro- 

 scope, that it consisted wholly of the siUceous shields of Diatomacese, 

 the same as found in the infusorial earth, excepting that the larger 

 disks in their perfect form were absent (Actinoci/clus Ehrenhergii and 

 Actinrtptychus undulatus). My conclusion is that they (and there 

 probably may be other forms) are too large to enter the root-capil- 

 laries. During the coming summer I will attempt, if possible, to 

 make micrometer measurements of both. 



The discovery of Diatomacete in their original form in this wheat- 

 straw precludes the possibility of the infusorial earth having under- 

 gone any chemical change in the soil, either by forming chemical 

 combination witli the alkalies or the earths, or by suff'ering physical 

 disintegration from any catalytic action of any salts present in the 

 soil. 



A7in. c& Maf/. K Hist. Ser. 4. Vol. xvii. 33 



