1890.] MICROSCOPICAL JOURNAL. 31 



As regards the necessity of a joint and the natural tendency of be- 

 ■ ginners to work with the instrument in its inclined position, Dr. James 

 cited an incident in his own experience. Some of his students pur- 

 chased cheap German stands unprovided with a joint. After working 

 with his instrument a few days one of the boys came to him one morn- 

 ing with a couple of boards ten inches square, hinged together on one 

 side, so as to permit the upper one to be set at any desired angle, and 

 to be used for a foot to the instrument. In a week every student had a 

 similar arrangement, and Worked with the instrument inclined. 



Dr. R. H. Ward explained what he saw in the laboratories of Con- 

 tinental Europe. As each of these is organized by a professor, there 

 are many personal preferences and local ideas brought out. Students 

 who work in the laboratories come to this country knowing no other 

 instruments, and are likely to continue the use of the same. European 

 students are loyal to their own dealers. Usuallv the makers supply 

 what is called for. A joint for inclination should be considered essen- 

 tial. Round stages are equal in every way to the square, and have 

 some advantages, as for rotation, the second stage being more easily ad- 

 justed. 



Dr. L. D. Mclntosch said that makers cater to the requirements of 

 trade. They could not sell instruments without a joint, and so do not 

 make them. Round stages are more easily made than square ones. 

 American instruments are certainly superior to those of foreign manu- 

 facture. 



Cleaning Diatoms.* 



By EDWARD S. NOTT, 



HAMBURG, N. Y. 



1. The material must be completely disintegrated by continued boil- 

 ing in a solution of sal soda. 



2. The disintegrated material should be sifted in a sieve made of 

 bolt-cloth, removing all the fine earths and broken forms. 



3. The remainder may have the greater part of the sand removed 

 from it by revolving it in an evaporating dish with water. 



4. The material, now mostly diatoms, should be boiled in acids. 

 First, in muriatic, then wash ; second, in nitric, then wash, and some- 

 times boil also in sulphuric acid. 



5. After washing all traces of acid away, boil once more in a solu- 

 lution of sal soda, wash and sift in a fine sieve of bolt-cloth. 



The object is to remove all the debris and waste material before using 

 the acids, as the result will be better and at a less expenditure of time 

 and labor. The stock should be kept in alcohol, and in mounting, the 

 best distilled water should be used. 



We desire to return thanks to Dr. Edward Gray, of Benicia, Califor- 

 nia, for the following interesting specimen : Seeds of OrtJiocarpiis 

 purpurasccns^ a description of which will be foimd in the Doctor's 

 paper published in the June, 1S85, number of this Journal. 



* Proceedings of Am. Soc. of Microscopists, vol. xi, p. 149. 



