grams of crystallized oxalic acid in 1 liter of distilled water. Add 5 c. 

 c. of cochineal solution as an indicator. Prepared by grinding to a fine 

 powder about 3 grains of good cochineal and macerating it with fre- 

 quent shakings with 250 c. c. of a mixture of 4 volumes of distilled 

 water and 1 volume of alcohol, 95 per cent., and filtering through Swe- 

 dish paper, and keep the solution in closed bottles. 



Introduce the prepared combustion tube into the furnace, letting the 

 open end project a little so as not to burn the cork, supporting the U- 

 tube by a clamp. The tube is then gradually heated, commencing at the 

 fore part, nearest the cork, and progressing slowly towards the tail. 

 Care must be taken to keep the fore part of the tube at a moderate red 

 heat throughout the process. Avoid heating the end that is drawn to 

 a point lest the internal pressure causes it to blow out. The coinbus. 

 tion should be conducted so as to obtain a steady and uninterrupted 

 flow of gas. When the tube is ignited throughout its whole length and 

 the evolution of the gas has ceased, attach the aspirator to the other 

 limb of the U-tube and start it slowly. Then break off the point of the 

 combustion tube; at the same time pat out the gas. Draw a slow cur- 

 rent of air through the apparatus for a few minutes, in order to sweep 

 all the rest of the ammonia into the acid. 



Remove the combustion tube, together with the U-tube, from the 

 furnace when the aspiration is completed, and break the combustion 

 tube close to the cork by allowing a fine stream of cold water to fall on 

 it. Remove the corks from the U -tube, and run in from another burette, 

 holding fifth normal soda solution, and determine how much of the fifth 

 normal oxalic acid solution used has been neutralized by the ammonia 

 thus obtained from the soil. From the data thus obtained the percent- 

 age of nitrogen contained in the soil maybe calculated. (Fres., 185.) 



DETERMINATION OF NITRIC ACID BY SCHLOESINtt'S METHOD. 



The following is the method adopted at the Rothamsted Laboratory 

 by Mr. R. Waringtou : * 



It is very important that the sample of soil should be immediately 

 dried when received in the laboratory, as, if this is not done, the quan- 

 tity of nitric acid found may greatly exceed that existing in the original 

 soil, as nitrification will be continually in progress whilst the soil re- 

 mains damp. The temperature at which the soil is dried has a marked 

 effect on the result. If a wet soil be dried in an air-bath at 100 C. the 

 nitrates present will be more or less destroyed, whilst drying by mere 

 exposure to the air is equally likely, in the case of surface soils at least, 

 to occasion a gain in nitrates. 



The following course has been adopted at Rothamsted : 



PREPARATION OF THE SAMPLE. 



The soil is broken up immediately it is received from the neld, and spread in trays 

 in layers about 1 inch in thickness; the trays are then placed in a storeroom, kept 



* Journ. Chem. Soc., Vol. xxxviii, p. 46^. ami Vol. xli. p. 345-3t>0. 



