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XIII. — On a Mode of Isolating the Siliceous Shells of Infusorial 

 Animals found in Ichaboe Guano. By H. Deane, Esq. 



(Read October 15, 1845.) 



Soon after the guano from Ichaboe reached this country, it was 

 found to contain the siliceous shells of infusorial (?) microscopic ani- 

 mals, allied to those brought from Richmond, in Virginia, and from 

 Bermuda. But the patient searching of many of my friends, was only 

 rewarded by the occasional appearance of a solitary Coscinodiscus, or 

 something analogous, until it occurred to me to decompose the guano 

 with nitric acid. The result was very satisfactory ; and the following 

 is the process I adopted. 



Take any convenient quantity of pure Ichaboe guano, and wash it by 

 repeated ablutions of distilled water, until the water is no longer 

 coloured, observing after each addition of water, that it must be well 

 stirred two or three times, and then allowed to settle for some hours. 

 When sufficiently washed, a small quantity of hydrochloric acid is to 

 be added to the water last used: this dissolves some portion of 

 it with effervescence, and causes a more perfect subsidence of that 

 which it does not act upon. After this, allow sufficient time for the 

 deposit to become well settled down; then, the clear liquor being 

 poured off as closely as possible without loss of the sediment, a quan- 

 tity of strong nitric acid, in the proportion of about two fluid ounces 

 to every ounce by weight of guano employed, is to be added. A 

 strong effervescence ensues, which is to be assisted by setting the 

 mixture in a warm place, at the temperature of about 200°, for six 

 hours, during which time, the greater part of the guano is dissolved. 

 After allowing it to cool for twenty-four hours, pour off the acid liquor 

 as closely as possible, and wash the sediment with an abundance of 

 distilled water. The finer portions of this sediment will contain all 

 the siliceous shells of the guano, perfectly freed from extraneous 

 matter. The accompanying slide, for the museum of the society, was 

 prepared in the manner just described, and contains many very beauti- 

 ful species, most of them well known, but many new both to myself 

 and others more experienced in this branch of microscopic obser- 

 vation. 



