80 S. W. Johnson on some points of Agricultural Science. 
all the mineral matters required by vegetation than would be needful 
to supply any average crop. Henneberg and Stohmann (iiber das 
Verhalten der Ackerkrume gegen Ammoniak u. Ammoniaksal- 
zen, Ann. der Chem. u. Pharm. evii, 170) found that when a soil 
had been saturated with ammonia, pure water removed it again 
to acertain extent. Thus 100 grams of soil were treated with 
200 c. c. of a solution of chlorid of bie rb nh (containing 0°693 
grams ammonia) and absorbed 0°112 grams of ammonia; on 
removing one-half of the aah oe ro substituting as much pure 
water the soil lost 0°009 s of ammonia as the result of the 
dilution: by again replacing “Swit water 100 c. c. of the thus 
diluted solution, 0-014 grams of ammonia were ice en gn from 
s—‘If sulphate of ammonia in very dilute solution, is brought 
in contact with soil saturated with, silicate of potash, and which 
does not give up a trace (?) of its potash to water toad it in- 
stantly dissolves a certain quantity of this alkali, which may 
easily detected by the common reagents.” 
iebig has not overlooked the case of aquatic plants whose 
roots do not enter any soil, for which, he remarks—‘“ there must 
ra 
It must be borne in mind that the amount of mineral (fixed) 
ingredients in a plant or crop is but a minute fraction esc 
to Boussingault ;;1,,; on the average, according to Law 
Gilbert 5755) of the quantity of water which a plant or crop 
under usual circumstances transpires during its season of growth. 
We are not surprised then, en einer eheita plants are sufficient- 
ly fed when their roots are m mee fe a unded by ordinary well 
water which is daily changed, or by distilled water mingled with 
a little vegetable ash into whi hich carbonic acid is daily con- 
aurey 
