Brown’s tubes

Heat Autoclaving or dry heat Temperature-sensitive coloured solution Sealed tubes partly filled with a solution which changes colour at elevated temperatures rate of colour change is proportional to temperature, e.g. Browne s tubes Temperature, time... 

Browne s steriliser tubes contain a liquid that undergoes a slow chemical reaction at elevated temperatures, changing from red to amber then green. Only when they are green has the correct temperature time combination elapsed. Several of these indicator tubes should be distributed in each batch of material to be sterilised. It is important when autoclaving liquids, to place a Browne s tube in a bottle of liquid as the conditions within such a bottle differ from those outside. Different types of Browne s tubes are available for sterilisation using steam or dry heat. Type I (black spot) tubes are... 

APPROX. VOLUME AND OPACITY (brown s tube NO.) OF INOCULUM PER 100 ML ASSAY MEDIUM... 

Forster Brown s report, 54 Hudswell lifts, 58-59 Lampson tubes, 62 Lifts, 58-59,67 Locomotives, main line, 60, 68 Main Surface Loading Platform (MSLP), 60,67 No. 6 shaft, 56 Powerhouse, 60-61 Railway adit, 18,58,70 Railway connection severed,... 

Nine months before, on the ioth of November 1977, an egg cell had been removed from one of the ovaries of a 30-year-old woman named Lesley Brown. She had blocked fallopian tubes, which prevented any egg cells released by her ovaries from becoming fertilized by sperm cells. Lesley Brown s removed egg cell was instead fertilized in vitro, literally in glass, in this case in a flat petri dish. Two and a half days later, when the fertilized egg cell had divided three times to produce a clump of eight cells, the clump (called a morula) was implanted into Lesley Brown s uterus to begin the usual 9-month gestation. 

Brown s Still-Head.—A modification of this apparatus, devised with a view to the better control of the temperature of the still-head, is described by Brown (2). The liquid to be distilled is boiled in the vessel a (Fig. 44) the vapour rises through the coil c, the temperature of which is that of a hquid boiling in the vessel e. The vapour from the hquid in e passes through the tube d to the worm condenser p, and the condensed liquid returns by the tube k to the bottom of the vessel e. 

Add 2 -3 drops of phenylhydrazine to about 2 ml. of Fehling s solution in a test-tube and shake the mixture vigorously nitrogen is evolved and reddish-brown cuprous oxide is precipitated. The reaction proceeds rapidly on gentle warming, more slowly in the cold. 

Place 10 ml. of 1% starch solution (prepared as described above) in a boiling-tube, add 2 ml. of 1% sodium chloride solution and place the tube in a water-bath maintained at 38-40 . Place about 5 ml. of water in a series of test-tubes and to each add a few drops of 1% iodine solution. Now add 4 ml. of the diluted saliva solution to the starch solution, mix well and note the time. At intervals of about 30 seconds transfer 2 drops of the reacting mixture, by means of a dropping tube, to one of the test-tubes, mix and note the colour. As in the previous experiment, the colour, which is blue at first, changes to blue-violet, red-violet, red-brown, pale brown, and finally disappears at this stage the solution will reduce Fehling s solution. If the reaction proceeds too quickly for the colour changes to be observed, the saliva solution should be diluted. 

A suspension of 0.40 mol of sodium amide in 300 ml of liquid ammonia was prepared as described in Chapter II, Exp. 11. To the suspension was added with swirling a mixture of 0.25 mol of CHgCeC-S-Ph (see Chapter IV, Exp. 14) and 40 ml of THE in about 2 min (note 1). Swirling was continued after the addition. Three minutes later (note 1) the stopper with glass tube was placed on the flask. The brown solution was forced through the glass tube and the plastic tube, connected to it under 400 g of finely crushed ice, which was contained in a 3-1 conical flask (see Chapter I, Fig. 3, and accompanying description of this operation). The flask was placed for... 

Chromium (II) also forms sulfides and oxides. Chromium (II) oxide [12018-00-7], CrO, has two forms a black pyrophoric powder produced from the action of nitric acid on chromium amalgam, and a hexagonal brown-red crystal made from reduction of Cr202 by hydrogen ia molten sodium fluoride (32). Chromium (II) sulfide [12018-06-3], CrS, can be prepared upon heating equimolar quantities of pure Cr metal and pure S ia a small, evacuated, sealed quartz tube at 1000°C for at least 24 hours. The reaction is not quantitative (33). The sulfide has a coordination number of six and displays a distorted octahedral geometry (34). 

FIG. 6-12 Correction factor for PoiseiiiUe s equation at low pressures. Curve A experimental curve for glass capillaries and smooth metal tubes. (From Brown, et al, J. Appl. Phys., 17, 802 [1.946].) Curve B experimental curve for iron pipe (From Biggie, Couiiesy of E. I. du Pont de Nemours [Pg.641]

These three tubes contain a mixture of N02 g and N204(g). The tube on the left is in an ice-water mixture. The centre tube is at room temperature. The tube on the right is in boiling water. Given that N02 g is brown, can you explain the shift in equilibrium Think about Le Chatelier s principle and the enthalpy of the reaction between the two gases. 

C. N-Hydroxy-4-(p-chlorophenyl)thiazole-2(3H)-thione. O-Ethyl S-[2-oximino-2-(p-chlorophenyl)ethyl]dithiocarbonate (56.0 g, 0.19 mol) is placed in a 500-mL round-bottomed flask that is equipped with a magnetic stir bar. Diethyl ether (120 mL) is added and the slurry is treated at 0°C in small portions with solid anhydrous zinc chloride, ZnClj, 79.1 g, 0.58 mol) at such a rate that the solvent does not boil constantly (Note 8). After the addition is complete, the flask is stoppered with a drying tube (CaCl2) and stirring is continued for 48 hr at 20°C. The reaction mixture turns into a dear, dark brown solution that solidifies toward the end of the reaction. The flask is immersed in an ice bath and treated dropwise with 5.5 M hydrochloric add (140 mL, Note 9). The precipitate dissolves immediately. Stirring is continued for 30 min at 0°C whereupon a tan-colored solid separates. This material is collected by filtration. It is washed with small portions of diethyl ether (total of 110 mL) and dried to afford 39.8 g (86%) of N-hydroxy-4-(p-chlorophenyl)thiazole-2(3H)-thione (Note 10). The crude material is transferred to a 2-L, round-bottomed flask equipped with a reflux condenser. 2-Propanol (760 mL) is added and the reaction mixture is heated to reflux. Once a dear solution is obtained the heat source is immediately removed (Note 11). The solution is allowed to cool to room temperature. Precipitation of N-hydroxy-4-(p-chlorophenyl)thiazole-2(3H)-thione is completed by immersing the flask for 30 min in an acetone-dry ice bath (-78°C). The product is collected by filtration and dried to afford 21.9 g (53.5%) of N-hydroxy-4-(p-chlorophenyl)thiazole-2(3H)-thione as tan crystals (Notes 12,13). 

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