ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
829 
Sulphuric Acid . — One of the most difficult determinations, as the 
occurrence of a precipitate with barium chloride by no means proves 
the presence of sulphuric acid. Crystals of potassium sulphate may bo 
obtained from a solution of the ash. 
Tartaric Acid . — May be precipitated by potassium acetate or calcium 
chloride. 
Behaviour of Fossil Teeth to Polarized Light.* — Dr. J. Schaffers 
obtained from experiments made on fossil teeth with polarized light 
results perfectly analogous to those previously obtained from fossil bone, 
and considers that the explanation of this optical effect is due to the fibrillar 
structure of both substances. The author’s results do not accord with 
those of Valentin, who found that fossil and recent teeth behaved in 
the same manner to polarized light, while the author considers that the 
reverse is the case. 
Bohm and Oppel’s Manual of Microscopical Technique.! — This 
little work is intended for beginners ; it is divided into two parts, the 
first of which deals with the Microscope and its manipulation, the 
second part is subdivided into general and special sections. In the 
former are considered methods of preparation, fixation, hardening, imbed- 
ding, sectioning, and staining. The special section deals systematically 
with the various organs and tissues. 
* SB. K. Akad. Wiss. Wien, xcix. (1890) pp. 146-52. 
t ‘ Taschenbuch der Mikroskopischen Technik.’ Miinchen, 1890, 8vo, 155 pp. 
Cf. Zeitschr. f. Wiss. Mikr., vii. (1890) pp. 175-6. 
