222 MEMORANDA. 
Mr. Collins has also brought out a cheap and portable col- 
lecting- -case, consisting of a neat 
japanned case, with sling-str ap for 
the shoulder, and containing three 
good-sized bottles, four test-tubes, 
Ne net, and dipping-tubes. A dip- 
ats ae ping-bottle, made to screw on to 
TTTTTTTMMTMN|+«=«stlhe: Same stick as the net, is also 
| made part of the kit. Another 
| kind is made to fit into a morocco 
ee satchel, which allows of space 
for botanical specimens. This 
is a very desirable addition to 
the adjuvanta of the microscopist. 
COLLINS’ COLLECTING CASE. 
On Cleaning iDiatoms.—There is often considerable diffi- 
culty in cleaning the diatoms contained in guano sufficiently 
to render it possible to mount the frustules without the 
troublesome process of selection, ‘The methods of Bailey 
and of Edwards are partially successful, but they injure 
the frustules a good deal, and leave amorphous matter 
in the shdes. The following plan has been found very 
successful in several instances, and is worthy of further 
trial:—Take a beaker of six or eight ounces capacity, put 
into it not more than two teaspoonfuls of guano, and 
fill it up within an inch of the top with a saturated solu- 
tion of carbonate of soda. Boil it for half an hour, wash the 
sediment well, pour off the last water very close, and pour in 
two ounces of hydrochloric acid. Boil for an hour, wash 
well, pour off the last water very close, and treat the sedi- 
ment with an ounce of strong sulphuric acid, let the acid act 
for about ten minutes, and then add cautiously some bicar- 
bonate of soda, either in solution or suspension in warm 
water, and shake well during the effervescence, taking care 
that the fluid does not overflow the edge of the beaker. 
Wash well, pour in with great caution two ounces of nitric 
acid, and when the effervescence has subsided add one or 
two pinches of chlorate of potash, and boil for an hour, or 
until the sediment has become white. If this does not take 
place in an hour, it might be well to commence the process 
anew ; but so far as the method has been tried, it has never 
failed. Then wash, and use the ordinary methods for sepa- 
rating the diatoms according to their specific gravities; that 
of Okeden, as described in Pritchard, is the simplest and 
best. ‘This process may seem to occupy a great deal of time, 
