22 MICRO-CHEMICAL REAGENTS. 



color. Hydrochloric acid is further valuable for 

 showing the nucleus of diatoms, etc. 1 



' Crystals based on carbonic acid emit bubbles of 

 this gas, when treated with hydrochloric acid, the 

 carbonates being converted into chlorides. On 

 the other hand, crystals based on oxalic acid dis- 

 solve without effervescence. 



Recently, Pringsheim 2 has employed hydro- 

 chloric acid as a reagent for hypochlorin, one of 

 the components of chlorophyll bodies, q. v. Newly- 

 cut sections are allowed to lie in the acid for sev- 

 eral hours, when the hypochlorin separates as 

 small semi-fluid exudation-masses, brownish or red 

 in color, at first nearly spherical, but afterward 

 forming needle-shaped crystals. 



ORGANIC ACIDS. 



ACETIC ACID. 



This acid 3 is used, in the form in which it is kept 

 by pharmacists, in various micro-chemical investi- 

 gations; e.g. it may replace hydrochloric acid in 

 Hanstein's method for clearing opaque meristem 

 (see the section on potassic hydrate, Cf. p. 1 1). The 

 sections, first rinsed in water, are placed in a drop 



1 Pfitzer: Bacillariaceen. Hanstein's Bot. Abhandl., I., Heft 2, p. 31. 



2 Monatsber. berlin. Akad., Nov. 1879. 



3 Dippel: Das Mikroskop, I., p. 277; II., p. 10. Nageli: Das Mikro- 

 skop, 1877, p. 476. Hanstein : Scheitelzellgruppe, 1868 ; Entwickelung 

 des Keimes. Bot. Abh., Bd. L, Heft i, p. 5. Strasburger: Studien 

 iiber Protoplasma, 1876, p. 5. 



