Airtight coverings

Fig. 4. Electrolyzer with rotating disk cathode. 1) Replaceable lead anodes 2) rotating cathode 3) axis of rotating cathode 4) pinion of cathode drive mechanism 5) mercury container 6) body of electrolyzer, 7) airtight cover.

Cover the dry gel with a protective plastic foil, cut it into 5 mm strips and store airtight at -20 °C (strips are stable for several months). 

As Maillard searched among the ash and molten material which had fallen through the grate, the academicians were confident that he would never see his diamonds again. When the airtight, glassy covering was broken away and the crucible opened, the tobacco pipe, the carbon dust, and the three diamonds were recovered intact. Hence it was evident that both heat and air were required for the destruction of the diamond (258, 260). 

Gutentag et al.17 showed chat CS, either dry or in solution, produced erythema and vesicles in the skin of human subjects. Covering the CS-treated area increased severity, and airtight compresses were more damaging than gauze pads. 

Shake the flask containing the crystals until any cake that may have formed is broken up and quickly pour the contents of the flask onto the Witte plate. Place the second funnel rim to rim with the first as a cover and bind the rubber tape around the joint to hold the two together by an airtight joint. Pump off the mother liquor and continue to pump air through the flask until... 

Cyanuric chloride reciystallization. Cyanuric chloride (30 g, 0.16 mol) is dissolved in hot petroleum ether (500 mL) with constant stirring in an oil bath. Heated petroleum ether is poured over a fluted filter paper and the solution of cyanuric chloride filtered into a 1-L conical flask. The saturated solution of cyanuric chloride is left overnight, covered, to allow formation of crystals. The crystals are filtered and dried under reduced pressure. The dried crystals are stable at room temperature in an airtight container. The yield is about 95%. 

Scoop up V2 tablespoon of the filling and place it on the bottom of a cooled cookie. Then cover the filling with another cooled cookie, pressing down lightly to form a sandwich. Repeat to fill all the cookies. Store the cookies in an airtight container for up to 2 days, or keep them, well wrapped, in the refrigerator for up to I week. 

A manual microfiltration apparatus (Fig. 3) has been made by the present authors for use with a CRC thimble. The apparatus is constructed of stainless steel with neoprene rubber seals. A hollow base holds a test tube for collection of the filtrate, if required, and has a connection for a vacuum pump. The top, which fits onto the base with an O ring, has on its upper surface a well to hold the CRC thimble and a support for the removable filter cover. The cover has a probe that is inserted into the solution to be filtered. When negative pressure is applied to the vacuum connection and the CRC thimble is held in place by the filter cover, the airtight seals enable solution to pass through the probe. 

Fig. 3. Microfiltration apparatus. 1, Stainless steel base 2, Stainless steel top 3, neoprene rubber seal 4, vacuum connection 5, CRC thimble 6, test tube for collection of filtrate 7, airtight filter cover with probe 8, airtight seating.

Chlorine gas is generated when chlorine bleach is mixed with sodium bisulfate (Sani-Flush). Pour a can of Sani-Flush in a baking pan, and level off the top of the pile. Punch a hole near Che bottom of the plastic bleach jug and place the jug in the center of the pan. A steady cloud of gas will be generated, the actual duration depending upon the rate of bleach flow. If It is necessary to direct the gas to a specific area, the generator can be covered with an airtight top fitted with a... 

The interlocking cover forms an airtight seal that keeps steam safely inside. 

To demonstrate how a gas at constant temperature can be used to do work, let s examine the action of a piston as shown in Figure 11.3. The piston inside the cylinder is like the cover of a jar because it makes an airtight seal, but it also acts like a movable wall. When gas is added, as shown in the top cylinder, the gas particles push out the piston rmtrl the pressure inside balances the atmospheric pressure outside. 

In these experiments the silver vessel which contained the substance to be examined had, of course, to be filled with hydrogen instead of with air, in order to facilitate equalization of temperature. To this end there was a little silver capillary in the cover which was rapidly closed airtight with a drop of solder after filling with hydrogen. The glass vessel containing the calorimeter had also to be filled initially with hydrogen, at about 1 cm. pressure, which was pumped off after the temperature of the calorimeter had fallen sufficiently low. 

Place samples in heavy-gauge aluminum moisture dishes approximately 55 mm diameter and 15 mm height. The moisture dishes should have slip covers and should be dried for 1 h at 103 or 130 C before using and then cooled in a desiccator. Place hot samples removed from the oven first in an airtight desiccator containing activated alumina or suitable desiccant. Make weighings to the nearest 0.1 mg after samples reach room temperature (usually 30 0 min). 

Bag Molding Bag molding is essentially an extension of the lay-up process. The lay-up structure is covered by a flexible airtight bag and either an external pressure is applied or vacuum is created inside the bag-mold enclosure. This improves the properties of the resultant composite by driving out volatile substances and increasing the volume fraction of reinforcement. 

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