20 METHODS OF ANALYSIS I Chap. 



mouth of which is fitted, by means of a rubber stopper, a section of glass tubing 10 

 cm. in length and 1 cm. internal diameter, which in turn is furnished with a side 

 tube extending through the condenser jacket (D), and connected by means of a rub- 

 ber stopper to the small trap (K), which is attached to the Meyer absorption appara- 

 tus (E) as shown in the figure. The Meyer absorption apparatus is provided with 2 

 large bulbs, each of about 250 cc. capacity, and 10 smaller connecting bulbs, each of 

 about 10 cc. capacity. The connections between the various bulbs should have an 

 internal diameter of 8-10 mm. A perforated rubber stopper carrying 2 short pieces 

 of capillary tubing each provided with rubber tubing and pinch-cocks (N and 0) 

 is fitted into the other opening of the Meyer absorption apparatus; (jY) is for the 

 addition of reagents, (0) is connected to the vacuum pump. 



All parts of the apparatus must be capable of withstanding a vacuum of approxi- 

 mately 70 cm. and be perfectly air tight. 



9 DETERMINATION. 



Place 5-20 grams of soil as prepared under 2 (depending upon the carbonate con- 

 tent as indicated by qualitative examination) in the flask (C), and connect up the 

 apparatus, but do not connect {A) to (B). Close the stop-cock (G) and the pnch- 

 cock (N) ; open the pinch-cock (0) and exhaust the apparatus to a vacuum of ap- 

 proximately 70 cm. Close the pinch-cock (0). Connect the barium hydroxid 

 container by means of the pinch-cock (A^ and rubber tube; open the pinch-co^k 

 (N) and allow sufficient barium hydroxid solution to flow into the Meyer absorption 

 apparatus to fill 3 or 4 of the small bulbs; close the pinch-cock (A''); substitute the 

 barium hydroxid container by the carbon dioxid-free water container; open the 

 pinch-cock (A'^) and add sufficient carbon dioxid-free water to fill all the small bulbs 

 and most of the lower large bulb. Through the separatory funnel (S), add 80 cc. of 

 carbon dioxid-free water to the sample in the flask (C), avoiding the entrance of any 

 air, open the pinch-cock (0) and heat to boiling, protecting the flask from the direct 

 fiame by a w^ire gauze with an asbestos center. Adjust the burner so that 2-3 min- 

 utes are required for the contents of the flask to reach boiling temperature and boil 

 until bubbles no longer pass through the Meyer absorption apparatus. Then close 

 the pinch-cock (0), and run into the flask (C), avoiding the entrance of any air, 

 20 cc. of the dilute hydrochloric acid through the separatory funnel which is then 

 connected with the tube {A). This proportion of hydrochloric acid plus the 80 cc. of 

 water previously added, gives an acid (2 to 100) for the decomposition of carbonates. 

 If the nature of the soil is such that a greater strength of acid is considered necessary, 

 an amount of acid (3 to 100) may be used for digesting the soil. Shake the Meyer 

 apparatus (E) gently, so that the liquid in the lower large bulb is brought into con- 

 tact with the gas therein, and open (0) carefully, but do not allow- more than a few- 

 bubbles to escape before shaking again. Repeat the operation several times until 

 bubbles no longer pass through the Mej^er apparatus (E) when (0) is opened. Leave 

 (0) open, and continue the boiling for about 25 minutes until carbon dioxid gas is 

 no longer evolved from the sample in the flask (C). Maintain a constant flow of 

 cold water through the condenser (D). Do not allow the boiling to become so violent 

 that liquid is drawn up into the condenser tube. If foaming is troublesome, add a 

 drop of non-volatile oil through the separatory funnel (B). When the evolution of 

 carbon dioxid has ceased, close (0) and break the vacuum by cautiously opening the 

 stop-cock (G) drawing in air through the tube (A). 



Disconnect the Mej^er apparatus (E) and filter by the Cain method^ as follows: 

 Prepare a filter by covering a perforated porcelain plate within a carbon funnel with 

 a layer of asbestos, and a laj'cr of ground quartz, both of which have previously been 



