Cleaning stoppers

Weigh out 1 g of granulated activated charcoal into each of five clean, stoppered 250cm conical flasks. Add lOOcm of 0.2M acetic acid... 

Extraction. To 1 ml of tissue homogenate is added 3.75 ml of chloro-form/methanol solution so that the ratio of chloroform/methanol/ water in the mixture is 5 10 4 (v/v/v). After thorough mixing, the mixture is converted to a biphasic system by addition of 1.25 ml of chloroform and a similar volume of potassium chloride reagent so that the ratio of components is 10 10 9 (v/v/v). After centrifugation at 2000 x g for 10 min, the upper phase is carefully aspirated so that the precipitate which forms at the interphase is undisturbed and a further 4.58 ml of the water chloroform/methanol mixture is added. After mixing, the phases are separated by centrifugation and the lower phase collected quantitatively into a clean stoppered test-tube and evaporated under N2 at 20°C. 

Add 1.0 ml of pure acetylacetone (2,4-pentanedione) to 50 ml of sodium carbonate solution in a clean stoppered flask. Mix and use within 15 to 30 min of preparation. Do not store this reagent. 

Samples of liquid for analysis shall be taken from the process stream into clean, stoppered borosrli-cate glass container(s). Reagents should be used so that the ions under test form stable suspensions or complexes. The resulting turbidity or intensity of color change should be determined by photoelectric colorimeter or spectrophotometer and compared to a curve prepared from standard solutions. 

When boring rubber stoppers, lubricate the borer well, either with aqueous glycerine or with vaseline. Then clean well and dry before using. 

Meanwhile, the organic compound can be prepared for analysis whilst the sealed end C (Fig. 72) of the Carius tube has been cooling dow n. For this purpose, thoroughly clean and dry a small tube, which is about 6 cm. long and 8-10 mm. w ide. Weigh it carefully, supporting it on the balance pan either by means of a small stand of aluminium foil, or by a short section of a perforated rubber stopper (Fig. 73 (A) and (B) respectively) alternatively the tube may be placed in a small beaker on the balance pan, or suspended above the pan by a small hooked wire girdle. 

Xanthhydrol. Prepare an amalgam from 9 0 g. of clean sodium and 750 g. (55 ml.) of mercury (Section 11,50,7, Method 1), and warm it to 50° in a 500 ml. Pyrex bottle. Add a cold suspension of 25 g. of xanthone in 175 ml. of rectified spirit, stopper the bottle and shake vigorously raise the stopper from time to time to release the pressure. The temperature rises rapidly to 60-70°, the sohd xanthone passes into solution, and a transient blue colour is developed. After about 5 minutes the alcoholic solution is clear and almost colourless. Shake for a further 10 minutes, separate the mercury, and wash it with 15 ml. of alcohol. Filter the... 

For a complete panel replacement, the refinisher starts with a panel preprimed in the appropriate stoving primer. For spot repairs or larger repairs without replacement of metal, there will be areas which have to be rubbed through to clean metal. Any indentations then have to be filled with a stopper or spray filler, probably based on unsaturated polyester resins and styrene, with cure initiated by mixing in an organic peroxide. After sanding, remaining bare metal areas are sprayed with a two-pack etch primer. 

The bottle should be clean and dry a little of the stock solution is introduced, the bottle well rinsed with this solution, drained, the remainder of the solution poured in, and the bottle immediately stoppered. If the bottle is not dry, but has recently been thoroughly rinsed with distilled water, it may be rinsed successively with three small portions of the solution and drained well after each rinsing this procedure is, however, less satisfactory than that employing a clean and dry vessel. Immediately after the solution has been transferred to the stock bottle, it should be labelled with (1) the name of the solution (2) its concentration (3) the data of preparation and (4) the initials of the person who prepared the solution, together with any other relevant data. Unless the bottle is completely filled, internal evaporation and condensation will cause drops of water to form on the upper part of the inside of the vessel. For this reason, the bottle must be thoroughly shaken before removing the stopper. 

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