1896.] MICROSCOPICAL JOURNAL. 233 



deposited on a simple glass slide and touched with the 

 linger, it will fall to dust. If this dust is distributed 

 over the slip by gentle taj)ping, and the surplus of diatom 

 powder is removed by tilting the slip, a thin, uniform; 

 evenly distributed layer of the largest and smallest in the 

 material will be found studding the slide in extreme 

 profusion. If this slide is then covered with a thin cover 

 glass, to which a drop of balsam has been applied, a slide 

 for study is thus perfected containing every form char- 

 acteristic of the deposit. I have found this to be a 

 direct and satisfactory process dispensing with the use of 

 acid treatment. One can prove the utility of the method 

 of separation or concentration by this modified form of 

 meciianical whirling at the same time getting rid of the 

 heavier sand and vegetable matter, otherwise difficult to 

 eliminate by acid treatment. When the whirling 

 principle is fully mastered, as outlined above, the secret 

 of successful concentration is within one's grasp. All 

 other accessory steps in diatom preparation present no 

 special difficulties of manipulation that cannot be readily 

 overcome. 



In order to illustrate the working advantages of the 

 analytical methods herein outlined, a reference to some 

 very recent study results conducted by employing the 

 processes already given in detail, I might recite that on 

 the occasion of the proposed Southern States Exposition 

 to beheld at Chicago, but which has since been postponed 

 indefinitely, it had been the intention, to have the 

 varied mineral resourses of the State of Alabama fully 

 represented. In accordance with this plan, I was en- 

 trusted with the duty of collecting such minerals as were 

 peculiar to south-western Alabama and south-eastern 

 Mississippi. The exhibits were to be made jointly by 

 the geological department of the state and the Mobile 

 and Ohio Railroad land department. While on this 

 mission in the field, I had opportunity to visit and study 



