45 
value to others possessing similar gatherings, I will give it in 
detail. 
The sounding, being inthe shape of a dry powder of a light 
greyish-ereen color was placed in a suitable glass vessel and 
moderately strong Liquor Potassa poured upon it. It was 
now boiled for a few moments until I saw that the lumps 
present in it were broken up anda light mud-like sediment 
was the result. The solution of Potassa must be, of course, 
apportioned in strength to the specimen under manipulation, 
such as consists of many lumps and much organic matter will 
require it of greater strength than that which is mostly cal- 
careous and siliceous. If it be used too strong some of the 
more delicate siliceous forms will be attacked or even, as I 
have occasionally found, entirely dissolved. After it had 
boiled for a short time, as I have said, I allowed it to stand 
until the mud had settled and a tolerably clear solution was 
left above it. I now poured off most of the Liquor Potassa 
and replaced it by a strong solution of Chloride of Soda, so- 
ealled. That sold by apothecaries under the name of ‘“ La- 
barraque’s Solution” will answer generally and is readily pro- 
cured. This I now boiled until I found its action to cease. 
By this means the mud is so much bleached as to become 
almost white. The Potassa at first has the effect of dissolving 
much of the organic matter present and, thus, breaking up the 
lumps and setting the shells free, and the Chloride of Soda 
solution bleaches them so that we have them clean and se- 
parated to such.an extent that under the microscope the in- 
dividual shells are easily recognised. I now proceeded to 
separate the larger from the smaller forms by means of the 
‘“ Hlutriation” process, which consists in first washing off 
thoroughly all the Potassa and Chloride of Soda with pure 
filtered or distilled water and shaking up the sediment ina 
glass about two inches high filled also with water. If now 
permitted to stand for a few seconds the larger forms and 
coarser sand settles and the supernatent liquid can be poured 
off into another larger vessel. Again water is added to the 
“first sediment and, in turn, removed and this is done as many 
as six or eight times until we see that the coarse sediment is 
