Add to each flask 30 ml chloroform (3.3) and 25 ml metaphosphoric acid solution (3.2) at 4 ĹźC.

Allo w the flask to remain in the water bath a further hour at 65 şC and shake every 10 minutes.

Pipette a 20 ml aliquot of the mixed solutions A and B (6.1.1) into a 500 ml boiling flask (5.1).

Allow the flask to remain in the water bath a further hour at 65 ĹźC and shake every 10 minutes.

P lace the flask in a boiling water bath for thirty minutes and then cool to approximately 35 şC.

Transfer to a 100-ml volumetric flask with ethanol (4.3) make up to the mark with ethanol and mix.

Weigh, to the nearest 0 7001 g, 2 75 g of the prepared sample and place it in a dry Kjeldahl flask.

For digestion, the Erlenmeyer flask shall be incubated at 40 to 41 _C for approximately four hours.

Place the flask in a boiling water bath for thirty minutes and then cool to approximately 35 ĹźC.

The gauze shall have a hole cut in the asbestos part of the same diameter as the base of the flask.

Remove the flask, cool to a temperature of about 20 ĹźC, make up to a volume of 500 ml with water.

Using a pipette, take 25 ml of Luff-Schoorl reagent (3.8) and transfer to a 300 ml Erlenmeyer flask;

Weigh 10 g of sample to the nearest 1 mg and place with 100 ml of water in a 200 ml graduated flask.

R emove the flask, cool to a temperature of about 20 şC, make up to a vo lume of 500 ml with water.

Pipette 10 70 ml (V1 ml) water into the flask and dissolve the evaporation residue (8.1) by heating.

Pour 5 g of 37 to 40 % formaldehyde solution into 1 000-ml volumetric flask and make up to 1 000 ml.

Dry the evaporation residue maintaining the flask for one and a half hours in the drying oven (4.3).

Weigh to the nearest 0,01 g, from 5 g to 10 g of the sample into a 250 ml conical flask with stopper.

Weigh out to the nearest mg 5 g of the sample into a 500 ml graduated flask with 250 to 300 ml water.

Collect the light petroleum extract in a dry, weighed flask containing fragments of pumice stone (1).

Volumetric flasks, 10 and 50 ml.

Reduce by evaporation to a volume of about 25 ml. Transfer quantitatively to a graduated 250-ml flask.

Transfer the contents with water into a 250-ml standard flask, make up to the mark with water and mix.

Cool immediately under running water to ambient temperature and, immediately, quantitatively transfer the contents from the Erlenmeyer flask into a graduated 500-ml flask with a jet of water (wash bottle).

Transfer 25 ml of the solution into a 250-ml standard flask and make up to volume with distilled water.

Weigh out, to an accuracy of 1 mg, 10 g of the sample and place it in a 500-ml graduated flask. 7.2.1.1.

Remove the stopper for an instant in order to balance the pressure and close the Erlenmeyer flask again.

Place the portion of the sample in the special flask (4) of the apparatus, fitted with a small tube of unbreakable material containing 10 ml of hydrochloric acid (3.1), and connect the flask to the apparatus.

Weigh 10 g of the sample to the nearest 1 mg and place with 100 ml of water in a 200 ml graduated flask.

C lose the flask with a rubber stopper and shake for 30 minutes at 20 ± 2 şC on a rotary shaker (5.2).

Pipette 25 ml of the sugar solution (6.2.2) into the conical flask and introduce two pumice chips (4.8).

Transfer the dispersion with water into a 100-ml standard flask, make up to the mark with water and mix.

Standard flasks, 100 and 1 000 ml

Weigh, to the nearest 0 7001 g, 5 g of the prepared sample and place it in a 500-ml graduated flask (5.1).

Take 50 ml of the solution and place in a small, dry, weighed flask containing fragments of pumice stone1.

Place the flask in the water bath set at 65 şC and shake every five minutes during the first half an hour.

Transfer the liquid quantitatively from the Kjeldahl flask to the distilling flask, add a few anti-bump granules of pumice stone (4.11) and make up with water to a total volume of approximately 350 ml. Mix and cool.

Weigh, to the nearest 0 7001 g, 1 g of the prepared sample and transfer to the 500-ml graduated flask (5.2).

Leave the flask for fifteen minutes in a thermostatically controlled water bath (for temperature see below).

Weigh 1 g of the sample to the nearest mg and place this portion of the sample in a 100 ml volumetric flask.

Place the flask in the water bath set at 65 ĹźC and shake every five minutes during the first half an hour.

In a one-litre graduated flask, of dissolve 432 g of dibasic ammonium citrate (C6H14N2O7) in 300 ml of water.

Mix the contents of the flask by turning it over at least five times, whilst keeping it closed with the hand.

Weigh, to the nearest 0 7001 g, 2 75 g of the prepared sample and place it in a 250-ml graduated flask (5.1).

Take 50 ml of the solution and place in a small, dry, weighed flask containing fragments of pumice stone (1).

Transfer both solutions (4.1.1 and 4.1.2) to a one litre volumetric flask and make up to one litre with water.

Mix the contents of the flask by swirling and place it in the boiling water-bath (5.2) for exactly 10 minutes.

Run into the boiling flask (5.1) from the burette a volume of standard dextrose solution equal to (X-0 73) ml.

Transfer this solution to a 1000 ml graduated flask (2.2.14), dilute to the mark with deionised water and mix.

Treat the residue with 10 ml hydrochloric acid (3.1) and transfer to a 500 ml graduated flask using warm water.