M. C, Lea on some new Manipulations. 379 
precautions, on the contrary, the mean of the first three differed 
from that of the second vie oy only a single milligram, or less 
than the sixtieth part of a 
o show that the latter aes were of no fortuitous joxeaisnis 
I may mention other instances. The distilled water 
ing with a given space was weighed sia times Ae nn ean 
trials gave 27091. To the above two rane a may add the fol. 
lowing: 
Table No, 3, mean of first : weighings, 2: of 4 more; 20515 
BOSH 4, 2°38 Mod 2-362 
sé “ 5, “ “ “ : 2-365, a“ 3 “ 2:370 
ac 4“ 6, “cc “ “ a sé 3°355, “ 9 “a 3°551 
it “ i; “cc “ “ 9 “ 3°577, “ 2 “ 3°577 
“ce “ 8, “ce “ “ 2 46 2°3605, “ 93 a“ 2°3630 
Comparing the first and second columns, that is, the first set 
of determinations, with the second we find that the maximum 
error was ‘005, and the minimum ‘0, or exact correspondence. 
The average of all the cases was 3°3 milligrams, or about one- 
twentieth of a drop. It would be difficult 4 8 burete —— to 
obtain greater accuracy than this, for if we are using, for 
ple, ten per cent solutions, the maximum error sand ani half 
a milligram of the reagent used, and the average error woul 
be one-third of a milligr 
I might greatly aiteod thie table of verifications, but I think 
what I have cited will be sufficient i bape that the i simple 
precautions which I here propose, viz., the positio Set bu- 
rette and card relatively to the light, oa still ee ye 
an eye-adjuster consisting of a slip of wood and sliding pst are 
suflicient to carry us to the sabain limits of accuracy whic 
the burette is capable of affording. It also shows that the bu- 
rette is entitled to great confidence where carefully used and 
when the reactions which mark the termination of the operation 
are perfectly distinct and sharp. 
LEE a hcjenccaime 
tered ¥ with a funnel of the Sinalless dimensions very speedy 
e followi . 
nel, and tied part at the neck, taking care that the string 
covers all the ey perfectly. A piece of india-rubber tube is 
then passed over the open end of the stem of the funnel: this 
piece ma sian: be several feet i in length, or it may be shorter, 
and the difference be made up by inserting a glass tube. The 
funnel and tube are then filled with water, the open end of the 
