Block bath heater

The power supply connected to the block bath heater is then switched on. 

Figure 119. The cross section of the isothermal storage testing device, a. To a temperature recorder b. Thermocouple c. Aluminium lid d. Aluminium block bath e. Glass closed cell f. Sample g. Heater.

All calorimeters consist of the calorimeter proper and its surround. This surround, which may be a jacket or a batii, is used to control tlie temperature of the calorimeter and the rate of heat leak to the environment. For temperatures not too far removed from room temperature, the jacket or bath usually contains a stirred liquid at a controlled temperature. For measurements at extreme temperatures, the jacket usually consists of a metal block containing a heater to control the temperature. With non-isothemial calorimeters (calorimeters where the temperature either increases or decreases as the reaction proceeds), if the jacket is kept at a constant temperature there will be some heat leak to the jacket when the temperature of the calorimeter changes. 

The samples were irradiated with 60Co gamma rays in an AECL Gammacell or in the pond facility of the AAEC, at dose rates from 0.1 to 2 Mrad h-1, to total doses from 0.1 to several hundred Mrad. Constant temperatures from 77° to 448°K (-196° to 175°C) were maintained using liquid nitrogen, slush baths, solid C02 and aluminum block heaters. 

Weigh accurately about 200 mg of a dned, extracted wood meal (40-60 mesh) with known moisture and extractives contents or 50 mg of a dned, purified lignin preparation The specimen, 7ml of 2M NaOH, and 0 4ml of freshly distilled nitrobenzene are placed m a 10-ml stainless steel bomb (Note 1) The bomb is sealed tightly with a screw cap fitted with a Teflon gasket and heated at 170°C for 2 5h m an electrically preheated (170°C), thermostated aluminum block with six holes to accommodate the cylindrically shaped bombs or in a thermostated oil bath The bomb is shaken occasionally and, after the heating period, is removed from the heater and cooled with ice water The oxidation mixture is transferred to a liquid-liquid extractor, and extracted continuously with CHCI, for 4h to remove nitrobenzene reduction products and any excess nitrobenzene The oxidation mixture is acidified to pH 3-4 with cone HC1, and further extracted continuously with CHCI, for 48 h The solvent from the second CHCI, solution is removed at 40°C under reduced pressure to obtain the nitrobenzene oxidation mixture The mixture is then dissolved m 5 ml of CH2C12 and transferred to a 10-ml volumetric flask The solution is made up to 10 ml... 

The quenching of mercury fluorescence was investigated using equipment described previously with a modification that the temperature of the fluorescence cell was kept within 1° at different temperatures, using a heater inserted in an aluminum block surrounding the cell. As before, the temperature of the mercury reservoir was kept within 0.1° using an ethyleneglycol bath. Table I shows an example of experimental data. 

Remove the paper with metal forceps and place i t in a specially clean 30-ml beaker (Sect. F) using the forceps to flatten the paper onto the bottom of the beaker. Add 1.0 ml of phosphoric acid and 1.0 ml of water from pipettes. Mix these two additions thoroughly. Put the coverglass onto the beaker and place it in a sand-bath or block heater carefully protected from any dust (Sect F). Heat the contents for 30 min at 100-110 C (Note c). 

Into five clean 30-ml beakers place glass filter papers moistened with 1 ml of phosphoric acid. Heat the beakers for 30 min on the sand-bath or block heater. To two beakers add 10.0 ml of sulphuric acid-dichromate oxidant and 4.0 ml of distilled water and to the remaining three beakers add 10.0 ml of oxidant and 4.0 ml of dilute glucose solution. Continue the method exactly as described in Section E, paragraphs 3-4 inclusive. Mix the two blank solutions (the extinctions of which against water... 

Add 1.0 ml of alcoholic potassium hydroxide and fit the 15-cm air condenser into the centrifuge tube containing the precipitate of magnesium carbonate and particulate matter obtained as described in Part IV. 2. Mix by shaking and transfer the centrifuge tube to a sand-bath or block heater. Warm for 30 min at about 100 C so that alcohol is refluxing part way up the condenser. 

Pipette 1.00 ml of the suspension, before any settling can take place, into a 20-ml Pyrex test tube. Add 10.0 ml of anthrone reagent from a pipette and mix the cells into the reagent with the buzzer or a clean glass rod. (Drain but do not rinse the rod.) Place the tube into a water bath or block heater at 100 C for a suitable period (Note b). 

Place the tubes in a sand-bath or block heater at 100 C for exactly 30 min (Note a). Remove the tubes and centrifuge the contents for 10 min at 5000 rpm. After centrifuging carefully withdraw the supernatant liquid with a capillary pipette attached to a vacuum source, being careful not to disturb the sedimented material (Note b). 

Place a glass stopper into the centrifuge tube and heat it in a sand-bath or block heater at 100 C for 4-8 hr (Notes a and fe). 

Try to submerge as much of the vial as possible into the oil bath or block heater. Alternatively, use an external heating source to prevent the sublimation. In some cases, adding a small amount of solvent might be successful Since the reaction vessel is fully contained by the reactor, applying an external heating source to prevent the sublimation is not possible. Adding a small amount of solvent could circumvent the problem... 

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