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 la generally surrounded by 

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

 together b}' threads. This stellate structure is also often brought out after 

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

 acid. 



5. No result. 



Agent. Time of Action. Eesnlt. 



«i 1 i/nr/w\ ,1 ( Grains bleached, but form 



Alcohol (95 %) 1 day. i 



•' ( remains. 



Steam 1 hour. 2 



Boiled in H^O 7 min. 2 



" then cold in HCl . . . 2 days. 3-)o^, , „ 



" HNO3 . . . 2 " 3[ ,'i?r/'y'^ 



Benzoic Acid. 2 " 3 3 s*^"^*"- 



H2SO4 cone 1 " Specimen destroyed. 



HjSO^ dilute 1 " 3 



HNO3 cone. . . 1 " Protoplasm contracted. 



HNO3 dilute . 1 " 1 



HCl 1 " 2 



HCl + HNO3 (3 parts HGl.l part HNO3) 1 " | ^™*°£™ "'"'''"'"" 



H2SO4 + HCl (equal parts) 2 " 3 



H2SO4 -f HNO3 " 2 " 3 



H2SO4 + HCl -I-HNO3 (equal parts) . . 2 " 3 



HCaHaOa 7 " 3 



H2C2O4 7 " 3 



H3PO4 7 " 2 



H.AH4O. (Tartaric acid) jS^^g'*^-;!*} 7 " 2 



H2Cr04 7 " 4 



Picric Acid 7 " 4 



Citric Acid 7 " 3 



Boracic Acid . . 7 " 3 



•t, • A -J ( sat. sol. in a sol. of lA parts ) - ,, . 



Benzoic Acid I n^^hPOi to 100 H^O } ^ ^ 



Benzoic Acid 2 " Grains bleached. 



Salicylic Acid 3 " 3 



Na5HP04 6 " 5 



Na(NH4)HP04 6 " 5 



NaHS04 6 " 5 



t Grains destroyed and pig- 

 NaOH 2 " } ment diffused through 



' the protoplasm. 



NH4OH 2 " 5 



K2CO3 2 " .5 



! Grains swell and become 

 homogeneous, but no 

 extrusion or escape of 

 the pigment. 



