704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Cleaning Diatoms from Marine Mud.* — Dr. G. H. Taylor places 

 a quantity of tho mud containing diatoms in a largo jar, which is then 

 filled with clean water, thoroughly shaken, and allowed to settle for 

 ten miuutes. One-half is then poured oft' into another jar, the first 

 refilled, shaken up, and again allowed to settle for ten minutes, when 

 the top portion is poured oft" into a third jar. This process is con- 

 tinued with the first jar until the water is clear after settling for ten 

 minutes. The material is then taken from the first jar in small quanti- 

 ties, and " sanded " by placing each portion in a shallow dish with a 

 moderate quantity of water, and rotating the dish so as to cause a 

 vortex in the water, when the diatoms and lighter matter will rise in 

 the water, and can be poured off into a bottle, leaving tho sand and 

 heavier particles behind. This process is repeated with each portion 

 until only sand is left in the dish. The " sanded " material 

 is now placed in an evaporating dish and dried. When dry, nitric 

 acid is poured upon it, and it is boiled until fumes cease to appear, 

 when a few grains of bichromate of potash are dropped in, and, after 

 boiling for a few minutes more, allowed to cool. When cool, the 

 acid is poured off, the dish refilled with sulphuric acid, boiled, and a 

 little bichromate of potash added. When the sulphuric acid has 

 thoroughly cooled, it is poured off, but not into icater, and the material in 

 the dish washed two or three times with clean water, stirring it up well 

 on each supply, and allowing it to settle each time before decanting. 



It is now again " sanded " by rotating the dish and pouring 

 off the top portion of the fluid into the bottle, adding more water 

 each time, until only sand is left in the dish. The material in the 

 bottle, now rich in diatoms, is shaken up, allowed to settle, and the 

 water poured off, until every trace of acid is removed, when the 

 material is returned to the clean evaporating dish, which is nearly 

 filled with water and boiled. A very small piece of caustic potash is 

 now added, and the boiling continued for two or three minutes, when 

 the contents are poured into the bottle. The material is now again 

 washed by shaking, settling for five minutes, and pouring off most of 

 the water, repeating the operation with fresh quantities of clean water 

 and decreasing the period of settling to two or three minutes, until the 

 water is free from any trace of alkali. The material is now again 

 " sanded " in small quantities at a time, and the lighter portion drawn 

 off by means of a dropping tube. The material thus withdrawn 

 contains almost all the diatoms. When all the material has been 

 treated in this way, it is extremely rich, containing but little sand 

 and a small amount of vegetable silica, but may be still further 

 improved by more time and labour. The material is washed several 

 times in distilled or filtered ruin-water, and about five to seven 

 minutes allowed for settling. About twenty drops of ammonia are 

 now added, the fluid well shaken, and the washing continued as 

 before. One or two more " sandings " with distilled water will now 

 give pure diatoms free from foreign matter or sand. Care should be 

 taken not to overlook the large forms of diatoms which frequently 

 adhere to the glass. 



* Proc. Amer. Soc. Micr., Eighth Ann. Meeting. 1S85, pp. 20S-10. 



