water, followed by boiling in dilute hydrochloric acid and finally 

 tlioroughly rinsing with water. 



GLYCINE or GLYCOCOLL is an amino acid used medicinally and is not to 

 be confused with the poisonous photographic developer glycin, 

 (p-hydroxyphenylaminoacetic acid). 



A MOLAL SOLUTION (m) contains one gram-molecular weight dissolved in 

 1000 grams of solvent. For ordinary aqueous solutions 1 ml. of water 

 is used as 1 gram. For other solutions calculate according to density 

 at the temperature used. 



A MOLAR SOLUTION (M) contains one gram-molecular weight in one liter 

 of solution. Dissolve the material in less than one liter and make up 

 to one liter in a volumetric flask. 



A NORMAL SOLUTION (acidimetry or oxidimetry) contains one equivalent 

 of the active reagent in grams in one liter of solution. The equivalent 

 value of any reagent will depend upon the conditions under which the 

 reagent is employed. It may or may not be the same as a molar solution. 



PERCENTAGE SOLUTIONS: Percent means parts in one hundred parts. These 

 solutions may be made up according to weight, volume, or any combination 

 of these. For example, a 3% solution of KCl contains 3 grams of the salt 

 in 100 grams of solution, or in 97ml. of water. A 3% solution can be 

 made up in any one of three ways: (a) 3 grams of KCl in a total volume 

 of solution of 100 ml.; (b) 3 grams in 100 ml. of water; (c) 3 grains in 

 97 grams of water. The third method will give precisely a 3% solution. 

 The first two methods do not give a 3% solution, but for concentrations 

 of 3% or less the error is too small to be of significance. For percent- 

 ages greater than 3% it is best to prepare the solution on the basis of 

 weight. For example, a 40% solution of NaOH is made by adding 40 grams 

 of NaOH to 60 grams of water. Some substances, e.g., alcohol, vary in 

 strength according to percent by weight or volume. Percentage solutions 

 (by weight) may be prepared with the solution balance. Place the bottle, 

 or bottle and funnel, on the pan and balance by means of the weight on 

 the ungraduated beam. Set the weight on one of the graduated beams and 

 weigh out the solute, then set for the amount of the solution and add 

 the solvent until the scale is balanced. The beams are graduated to 

 facilitate the preparation of percentage solutions but the balance 

 may be used to advantage for the preparation of other solutions. 



The dilution of percentage solutions (aqueous solutions by weight) 

 can be accomplished easily by taking the number of milliliters 



