Warming, atmosphere

Dr. Bostock s summary is as follows In order to procure an ink which may he little disposed either to mould or to deposit its contents, and which, at the same time, may possess a.deep.black hue not liable to fade, the gells should be macerated for some hours in hot water, and the fluid, filtered tire filtrate should, be then exposed for about fourteen, days to a warm atmosphere, when any fungoid growth that may be observed must, be removed. A solution of sulphate of iron is to be. employed which has been boiled, or. exposed for some time, to the air, and in which there is consequently an admixture of sesquioxide of iron.. If the infusion of galls be made considerably stronger than is generally directed, the ink formed in this manner will not necessarily require the addition of a mucilaginous substance to render it of a proper consistence. 

Temperature. When moved into a warm atmosphere, cold containers, wads, closures, and so on will require time to adjust to the new temperature. 

Ferrous copper sulphate, (Fe, Cu)S04.H20, or CuS04.2FeS04.3Ha0, occurs in yellowish brown crystals which are not hygroscopic in ordinary air, but take up water in a warm atmosphere saturated with moisture.6... 

The sample is mixed and heated to 80-90 °C on a magnetic stirrer. Then precipitation of calcium and strontium phosphates in alkaline medium (pH = 8 - 9) is performed by adding concentrated ammonium hydroxide. Precipitate is allowed to settle for at least 2 hours to one night. Then the supernatant is discarded. The precipitate is collected in a centrifuge tube and rinsed with alkalized water. Precipitate is dried in a warm atmosphere at 80°C. 

DF2 series. These tests are identical to DFl but will use warm atmospheres in the receiver, which will be heated by steam condensation and electrical heaters. This series will study steam-air-hydrogen mixtures at tenqieratures of300 to 400 K. 

The oxime is freely soluble in water and in most organic liquids. Recrystallise the crude dry product from a minimum of 60-80 petrol or (less suitably) cyclohexane for this purpose first determine approximately, by means of a small-scale test-tube experiment, the minimum proportion of the hot solvent required to dissolve the oxime from about 0-5 g. of the crude material. Then place the bulk of the crude product in a small (100 ml.) round-bottomed or conical flask fitted with a reflux water-condenser, add the required amount of the solvent and boil the mixture on a water-bath. Then turn out the gas, and quickly filter the hot mixture through a fluted filter-paper into a conical flask the sodium chloride remains on the filter, whilst the filtrate on cooling in ice-water deposits the acetoxime as colourless crystals. These, when filtered anddried (either by pressing between drying-paper or by placing in an atmospheric desiccator) have m.p. 60 . Acetoxime sublimes rather readily when exposed to the air, and rapidly when warmed or when placed in a vacuum. Hence the necessity for an atmospheric desiccator for drying purposes. 

Both forms sublime very readily, even at room temperature a small sample on exposure to the air will completely volatilise in a short time, particularly on a warm day or if the sample is exposed to a gentle current of air. Hence the above method for rapid drying. A sample confined in an atmospheric desiccator over calcium chloride rapidly disappears as the vapour is adsorbed by the calcium chloride. A sample of the hexahydrate similarly confined over sodium hydroxide undergoes steady dehydration with initial liquefaction, for the m.p. of the hydrated-anhydrous mixture is below room temperature as the dehydration proceeds to completion, complete resolidification occurs. 

The vapour pressure of the bromine should be maintained at about half an atmosphere (vapour pressures at 35° and 40° are 324 and 392 mm. respectively). If the water bath becomes too warm, it should be cooled immediately with ice, as otherwise more bromine will va lourise than can combine with the hydrogen present. 

Maleic acid may be prepared by warming malic acid with acetyl chloride, distilling the mixture under atmospheric pressure to isolate maleic anhydride, and hydrolysing the latter by boding with water. 

Vinylacetic acid. Place 134 g. (161 ml.) of allyl cyanide (3) and 200 ml. of concentrated hydrochloric acid in a 1-htre round-bottomed flask attached to a reflux condenser. Warm the mixture cautiously with a small flame and shake from time to time. After 7-10 minutes, a vigorous reaction sets in and the mixture refluxes remove the flame and cool the flask, if necessary, in cold water. Ammonium chloride crystallises out. When the reaction subsides, reflux the mixture for 15 minutes. Then add 200 ml. of water, cool and separate the upper layer of acid. Extract the aqueous layer with three 100 ml. portions of ether. Combine the acid and the ether extracts, and remove the ether under atmospheric pressure in a 250 ml. Claisen flask with fractionating side arm (compare Fig. II, 13, 4) continue the heating on a water bath until the temperature of the vapour reaches 70°. Allow the apparatus to cool and distil under diminished pressure (compare Fig. II, 20, 1) , collect the fraction (a) distilling up to 71°/14 mm. and (6) at 72-74°/14 mm. (chiefly at 72 5°/ 14 mm.). A dark residue (about 10 ml.) and some white sohd ( crotonio acid) remains in the flask. Fraction (6) weighs 100 g. and is analytically pure vinylacetic acid. Fraction (a) weighs about 50 g. and separates into two layers remove the water layer, dry with anhydrous sodium sulphate and distil from a 50 ml. Claisen flask with fractionating side arm a further 15 g. of reasonably pure acid, b.p. 69-70°/12 mm., is obtained. 

Nitrobenzene (and many other liquid organic compoimds containing nitrogen) is appreciably toxic and its vapour should not be allowed to escape into the atmosphere of the laboratory the delivery tube of the condenser should pass well into the mouth of the receiver flask. The liquid is also a skin poison if it Is accidentally spilled on the skin, it should be removed by washing with a litt e methylated spirit, followed by soap and warm water. 

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