198 SELECTED NOTES FROM 



diatoms, it contains plates of Synapta and wheels of Chirodota 

 violacea. It is an extremely pretty object when viewed under the 

 microscope, many of the diatoms being iridescent. Some may 

 look upon such a production as waste of time. If of no further 

 use, it stands as a testimony to a wonderful amount of patience, 

 labour, and dexterity. I introduce it to show what may be done 

 with diatoms by enthusiastic diatomists. J. R. L. Dixon. 



Diatomaceous Material, To Treat.— Mr. Allen has asked me to 

 give my method of treating Diatomaceous Rock, such as Oamaru, 

 etc. 1 give that which Mr. Grove (of Oamaru renown) has given 

 me. It may not prove of much use to our advanced manipu- 

 lators, but it may be useful to those who are beginning to work 

 among Diatoms — that most fascinating study. 



Break up the rock with a knife (or otherwise) into thin slices. 

 Get a little sulphate of soda (Glauber's salts), and cover some of 

 the slices with the salt heaped up, in a small evaporating dish ; 

 sprmkle over it a very few drops of water; heat over a lamp till 

 the salt melts. Take away the lamp and let it all crystallise ; if it 

 does not, drop on a dry crystal, and it instantly will do so. When 

 cool, put in a little water and warm again, and if it does not fall 

 into pieces evaporate the water, and let it crystallise again ; then 

 wash well and boil in sulphuric acid, etc., as usual. After good 

 washing, boil again with a very small bit of caustic potash for two 

 minutes only, and then pour into dilute muriatic acid. It should 

 then be clean. In lieu of an evaporating dish, the top of a cocoa- 

 tin may be used, and the whole put on the bars of the fire-grate. 



Decanting. — It is here that the trouble begins. Get some 

 small beakers about an inch and a-half in diameter and three 

 inches deep. If there is coarse, heavy sand, give half a minute 

 eacli time to settle. Do not pour off too closely at first, and after 

 two or three decantings you will be able to pour off clear. When 

 the water becomes quite clear, stop and examine the sand to see if 

 there are any large diatoms in it. If not, throw it away, and 

 when the decanted stuff is quite settled down in the large vessel, 

 into which you have poured your decantings, pour off all the water 

 you can without disturbing the bottom, and then giving the vessel 

 a good shake, pour the sediment back into the small beaker, and 

 repeat the decanting process at two minutes' interval. Proceed as 



