NOXIOUS GASES. 



475 



tive to the systematic cultivation of plants in such cases in the 

 impure air of manufacturing towns. In the glass cases, now 



stellate appearance. In the latter case each grain is generally surrounded by 

 an irregular mass of colored protoplasm, these masses being often connected 

 together by threads. This stellate structure is also often brought out after 

 dissolving out all the coloring-matter by prolonged treatment with beuzoic 

 acid. 



5. No result. 



Agent. Time of Action. Result. 



( Grains bleached, but form 

 Alcohol (95%) Iday.j remains. 



Steam 1 hour. 2 



Boiled in H. 2 7 min. 2 



then cold in HC1 ... 



- HN0 8 . . , 



" " " BenzoicAcid. 2 



U.,S0 4 conc 1 " Specimen destroyed. 



KUS0 4 dilute 1 " 3 



HN0 8 cone 1 " Protoplasm contracted. 



HN0 8 dilute 1 " 1 



HC1 1 " 2 



( Protoplasm much con- 



HC1 + HN0 8 (3 parts HC1, 1 part HN0 3 ) 1 " j tracted. 



H 2 S0 4 4- HC1 (equal parts) 2 " 3 



H 2 S0 4 + HN0 8 " 2 " 



H a S0 4 + HC1 + HN0 8 (equal parts) . . 2 " 



HC 2 H 8 2 7 ' 



HAO* j ; 



H 8 P0 4 7 * 2 



H 2 C 4 H 4 6( Tartarica C id) {SR^} 7 2 



H 2 Cr0 4 7 



Picric Acid 7 



Citric Acid 7 ' 



Boracic Acid 7 ' 



. . , ( sat. sol. in a sol. of 1^ parts ) , l 



Benzoic Acid j N^ H pC) 4 to 100 H 2 J 1 



Benzoic Acid 2 " Grains bleached. 



Salicylic Acid 3 " 



Na 2 HP0 4 6 " 



Na(NH 4 )HP0 4 6 " 



NaHS0 4 6 " 



f Grains destroyed and pig- 



N QTT 2 " - } ment diffused through 



( the protoplasm. 



NH 4 OH 2 " 



K Of) 2 " 5 



( Grains swell and become 

 1 homogeneous, but no 



Ether ^ ^ extrusion or escape of 



' the pigment. 



