167 
Metuop of Creanine Diatomaces. 
By Artuur M. Epwarps, New York, U. S. 
Tuovucuthere are many methods that have been devised for 
cleaning deposits of Diatomacez, none has proved to be per- 
fect in all its details; that one that appears nearest so being 
that which I give below: It is well known that the ordinary 
method given in the books, of boiling in nitric acid alone, is 
extremely unsatisfactory, as it does not remove all the or- 
ganic matter that may be present in the deposit, and this 
is more particularly apparent when treating guanos for the 
purpose of obtaining the forms contained in them. Some 
few years back Bailey published, in the ‘ American Journal 
of Science,’ a plan which seemed to meet all the wants of 
microscopists. ‘This method was by removing all the organic 
matter through the agency of sulphuric acid and chlorate of 
potassa. In this process, however, at first a bisulphate of 
potassa is formed, which, when we attempt to wash it out 
with water, is converted into neutral sulphate and free sul- 
phuric acid. The neutral sulphate of potassais a salt soluble 
only with difficulty, so that it becomes almost impossible to 
remove it entirely and leave the Diatomacez perfectly clean. 
It is to obviate this trouble that the following method has 
been devised, and, as it has beenin constant use for over two 
years, with invariable success, it can be confidently recom- 
mended to microscopists. 
It was first used in the case of guano, about the most 
difficultly manageable of all Diatomaceous deposits, and, 
therefore, will be given here as used for that substance, the 
difference of manipulation necessary to be used when it is 
required to clean earths or tidal muds being very slight and 
sufficiently apparent without mentioning them here. 
The guano is freely exposed to the action of the air during 
several days or weeks, according to whether it be rich in 
moisture and organic matters or otherwise, and also according 
to the amount of dampness present in the atmosphere; thus, 
in summer it requires but little exposure to bring the guano 
to a proper state, whilst, in winter, it will require several 
weeks. It is thus exposed until it has become perfectly dry, 
and crumbles to a fine light fawn-coloured powder. It is 
then washed several times in water that has been carefully 
filtered through chemists’ filtering paper. This filtered, is 
