United States or Panama ? Vote for the TOP Country of the Week !
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.
A flask may, of course, be graduated for both contents and delivery by placing two graduation marks upon it. PROCEDURE. To calibrate a flask for !contents!, proceed as follows: Clean the flask, using a chromic acid solution, and dry it carefully outside and inside.
From this report it appears that metallic pigments of a highly dangerous and even poisonous character, containing chromic acid, lead, copper, mercury, and arsenic, are commonly used in the colouring of such articles." If a child be never allowed to eat cakes and sweetmeats, he will consider a piece of dry bread a luxury, and will eat it with the greatest relish.
Barium sulphate, 100 parts; chromic oxide, 20 to 50; finished lacquer, 40 to 50; solvent, 20. This is dried for about 10 minutes at 160° C. Yellow. Barium sulphate, 100 parts; lead chromate, 40; finished lacquer, 40; solvent, 20. This is dried for about 15 minutes at 150° C. Almost all pigments other than the above-mentioned are blackened by contact with lacquer or suspend its drying quality.
Utensils lacquered with this lacquer are dried for about an hour at 130° to 140° C. Red. Vermilion, 10 parts; finished lacquer, 4; solvent, 2. This lacquer is dried for about an hour at 130° to 140° C. Khaki or Dirty Yellow. Barium sulphate, 100 parts; chromic oxide, 3; finished lacquer, 20 to 25; solvent, 15. This lacquer is dried for about half an hour at 160° C. Green.
You see here I can pour off the supernatant liquid clear, leaving our silver and gelatine as a clot at the bottom of the vessel. Another action of chromic acid is, that it destroys the action of light on silver bromide, so that up to this point operations can be carried on in broad daylight.
So that by treatment with chromic acid in the cold nearly the whole of the carbon remains undissolved with the cold-rolled and annealed disks, but only about one-sixth of the total carbon is left undissolved in the case of the hardened disk. The authors then give a resume of previous work on the subject.
From the acids in insoluble and a few other compounds, chromic, arsenic, and arsenious acids, by fusion with carbonate of soda in presence of carbonic acid gas; borate of manganese is readily decomposed when the boracic acid is to be determined by boiling with solution of potassa, dissolving the residue in hydrochloric acid and precipitating the manganese as binoxide.
“I have something to say to you,” said Daniel, as he entered the room. His eyes gazed on the walls and at the few cheap, ugly, banal objects that hung on them: a newspaper-holder with embroidered ribbons; a corner table on which stood a beer mug representing the fat body of a monk; an old chromic print showing a volunteer taking leave of his big family as he starts for the front.
Ferrous salts may be promptly and completely oxidized to ferric salts, even in cold solution, by the addition of potassium bichromate, provided sufficient acid is present to hold in solution the ferric and chromic compounds which are formed. The acid may be either hydrochloric or sulphuric, but the former is usually preferred, since it is by far the best solvent for iron and its compounds.
Word Of The Day