724 



Hydrochloric Acid and Chlori.n. 



Besides sulfur, hard coal also contains chlorin in the form of sodium 

 chloride The chlorin content varies between o.i to 2.0 per cent. Leadbetter 

 found in hard coal 0.009 to 0.028 per cent, of chlorin'-. This, however, could 

 not be proved in the ash and must, therefore, have been forced out with the 

 volatile substances. Meinecke has also directly proved the presence of 

 chlorin in the j^ases of blast furnaces" and Smith* calls attention to the 

 chlorin content of rain water in regions where hard coal is burned in consid- 

 erable amounts. According to these statements, therefore, we must not 

 consider any single injurious factor in the smoke of hard coal but dilVcrent 

 combinations of several factors. The difference will depend, on the one 

 hand, on the composition of the coal and, on the other hand, on its use 

 industrially. 



Because of the rapid formation of hydrochloric acid from chlorin in the 

 presence of moisture and light both these factors must be treated together. 

 In connection with sulfuric acid, mention has already been made of the 

 impoverishment taking jjlace possibly from the continued action of hydro- 

 chloric acid in the soil. The action of direct solutions of chlorin alkalies 

 will be mentioned in connection with cooking salt. The action on the plant 

 varies according to its species, the season of the year, or the place and 

 individual development. In general, this results in a bleaching and drying 

 of the leaf edges, or also of the intercostal fields in which chlorin vapor acts 

 more quickly than does hydrochloric gas. In contrast to sulfurous acid, 

 however, dry leaf edges preponderate here. It was observed in the experi- 

 ments made by Ramann and Sorauer (see Sulfurous Acid) that spruces 

 sprinkled with water absorbed, on an average, less chlorin than plants not 

 moistened. 



The studies on the changes in anatomy have up to the present led to 

 contradictory results. Thus Lindau^' observed in Abies an alteration only 

 at and near the stomata, while Kinderman*' confirms the investigations of 

 Leitgeb and Molisch, that the guard cells possess the greatest power of 

 resistance to injurious factors (among others, acids), which probably arises 

 from a special constitution of the cytoplasm. 



Because of the uncertainty of results up to the present time, I will 

 repeat here briefly the results of my own studies on grain and spruce'. At 

 first the heavy general falling ofif in reproduction which the plants undergo, 

 because of the hydrochloric vapors, and which manifests itself in the quan- 

 titative proportions and the formation of the grain, has been found to be very 



1 Hasenclever, tJbcr die Beschadiffung: der Vcgretation durch saure Gase. 1879, 

 p. 9. Berlin, Spring-er. 



2 Chemical News 1860, No. 46. 



3 Dingler'.s Journal 1875, p. 217. 



4 Bericht uber die Entwicklung der chem. Industrie von A. W. Hofman, 1875. 



5 I.oc. cit., p. 244. 



6 Kindermann, V. Uber die auffallende Widerstandskraft der Schliesszellen 

 geg-en schadliche Einflusse; cit. Just. Bot. Jahresber. 1902, II, p. 6.53. 



7 Sorauer, P. Beitrag zur anatomischen Analys^e rauchbeschadigter I'flanzen. 

 Jjandwirtsch. Jalirbiicher 1904, p. 587. 



