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It is plain that any temperature which is deemed most convenient might be chosen for a particular laboratory, but it cannot be too strongly emphasized that all measuring instruments, including burettes, pipettes, and flasks, should be calibrated at that temperature in order that the contents of each burette, pipette, etc., shall be comparable with that of every other instrument, thus permitting general interchange and substitution.
PROCEDURE. Rinse a previously calibrated burette three times with the hydrochloric acid solution, using 10 cc. each time, and allowing the liquid to run out through the tip to displace all water and air from that part of the burette. Then fill the burette with the acid solution. Carry out the same procedure with a second burette, using the sodium hydroxide solution.
"So much for this. Without excepting the new infamy of Cabrion, I am going at once to finish with that brigand. You will see what impudence! When old Burette was arrested, and we knew that Bras-Rouge, our landlord, was trapped, I said to my old darling, 'You must trot right off to the proprietor, and tell him that Bras-Rouge is locked up. Alfred set out.
The graduations are usually numbered in cubic centimeters, and the latter are subdivided into tenths. One burette of each type is desirable for the analytical procedures which follow. The inner surface of a burette must be thoroughly cleaned in order that the liquid as drawn out may drain away completely, without leaving drops upon the sides.
From a burette divided into 0.1 c.c. a solution of caustic soda is poured with continual gyration of the flask into the tinged liquid, and the percentage of combined iodine ascertained by difference; for this purpose 20 c.c. of mercury iodo-chloride are tested, on introduction of a solution of potassium iodide and starch, previously to its use as reagent.
Then run in the permanganate solution from a pipette or burette to determine roughly the amount required. Strong sulphuric acid also decomposes the oxalic acid. The excess of ferrous iron may also be determined by titration with potassium bichromate, if desired. The chlorine generated by the pyrolusite is passed into a solution of potassium iodide.
This is best accomplished by treating the inside of the burette with a warm solution of chromic acid in concentrated sulphuric acid, applied as follows: If the burette is of the "plain" type, first remove the rubber tip and force the lower end of the burette into a medium-sized cork stopper.
Madame Burette knew the housekeeper of the notary; she gave me a letter to her, in which she strongly recommended Louise. Cursed cursed be that letter; it has caused all our misfortunes. So, sir, this is the way my daughter went there."
PROCEDURE. Weigh out into 500 cc. beakers two portions of about 0.150-0.175 gram of potassium bromate. Run in thiosulphate solution from a burette until the color of the liberated iodine is nearly destroyed, and then add 1 cc. or 2 cc. of starch solution, titrate to the disappearance of the iodo-starch blue, and finally add iodine solution until the color is just restored.
Run in the thiocyanate solution from a burette, with constant stirring, allowing the precipitate to settle occasionally to obtain an exact recognition of the end-point, until a faint red tinge can be detected in the solution. From the data obtained, calculate the relation of the thiocyanate solution to the normal.
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