Metals and'Plants. 
461 
grew just enough to show their tips, after the fashion of the 
iron plant. 
As to the condition of the metals themselves at the end of 
the experiment, there was no visible change in the gold, plat¬ 
inum, palladium, silver, nickel, tin, antimony, (sulphur, car¬ 
bon), rhodium, chromium, indium, tellurium, (selenium), and 
ruthenium, tungsten, and boron,— the last three being in form 
of powder. The aluminum was not quite as bright as at first; 
the copper, of a little darker hue; the cobalt, tarnished olive 
green. The solution containing iron was brownish yellow, 
and contained a yellow precipitate — in part probably basic 
carbonate of iron, — with which the metal was thickly coated. 
The cadmium was badly corroded, the discoloration being 
very likely due to basic carbonate. Thallium was also cor¬ 
roded, of a blurred grayish appearance; the solution acquired 
a very pale lavender tint, but contained no precipitate. Zinc 
was badly discolored, by its basic carbonate. Magnesium was 
much discolored; there were hydrogen bubbles on the metal, 
and the sides of the beaker, and the alkalinity of the water 
was equal to 0.0075 Normal. According to Kahlenberg and 
True (9. P. 95) a concentration of 0.005 N. of hydroxyl ions is 
about sufficient to kill in twenty-four hours. The water in 
which lead had been placed contained a very copious precipi¬ 
tate of basic carbonate of lead, which covered the bottom of 
the beaker and coated the metal. The change in the sticks of 
bismuth was slight, the lustre having acquired an olive tint. 
The mercury surface was somewhat tarnished. The water con¬ 
taining sulphur showed a trace of sulphuric acid with the 
barium chloride test, but the free acid was only equal to 
0.15 c.c. N. per liter. Iodine colored the water the character¬ 
istic shade, and diffused upward slowly, staining the paraffine 
on the wall of the beaker as it went. Manganese became 
covered with a brown precipitate — probably oxyhydrate of 
manganese,— which was also deposited on the bottom of the 
beaker. After a time white flakes on the arsenic betrayed the 
formation of arsenious oxide. 
