1839.] 



On Chemical Tests. 



285 



xc. It is, in some cases, convenient to convert the muriates of lime, 

 and magnesia into sulphates, by pouring upon them excess of sulphuric 

 acid, evaporating to dryness, and heating the dry mass red hot. The 

 sulphate of magnesia may then be almost completely separated from the 

 sulphate of lime, by a small quantity of cold water; or a saturated so- 

 lution of sulphate of lime may he uspd, which takes up the sulphate of 

 magnesia, and leaves the sulphate of lime. 



xci. The residue (c) insoluble in alcohol, may contain chloride of 

 sodium, sulphate of soda, sulphate of magnesia, and sulphate of lime ; 

 digest it in ten parts of boiling distilled water, which, when cold, will 

 have taken up every thing but sulphate of lime, of which an inapprecia- 

 ble portion only will have been dissolved ; separate the solution into 

 two equal portions, a and b : which may afterwards be further diluted. 



xcn. To a add nitrate of silver, and wash and dry the precipitate, 

 which is chloride of silver, 146 parts indicate 60 of chloride of sodium. 



xcm. To b add acetate of baryta as long as it occasions a precipitate, 

 which is sulphate of baryta, (e) and which is to be separated, dried, and 

 weighed. 117 grains are equivalent to 72 of dry sulphate of soda and 60 

 of dry sulphate of magnesia. 



xciv. In order to ascertain the quantity of magnesia present, and 

 consequently the quantity of sulphuric acid belonging to it, evaporate 

 the liquid filtered off the barytic precipitate (e) to dryness ; it will con. 

 tain chloride of sodium, acetate of soda, acetate of magnesia, and, pro- 

 bably, a portion of the added acetate of baryta; ignite the dry mass, and 

 wash it to separate the chloride of sodium and the soda ; magnesia and 

 carbonate of baryta will remain insoluble, upon which pour dilute sul- 

 phuric acid ; digest, filter, and evaporate the clear liquor to dryness ; it 

 is sulphate of magnesia, equivalent of course to the original portion 

 of the salt ; deduct the sulphuric acid contained in it from the whole 

 in the precipitate (<?), and the remainder will give the quantity united to 

 the soda. 



xcv. To estimate the quantity of sulphate of lime in the water, the 

 residue of the evaporation of one pint may be washed with cold saturat- 

 ed solution of sulphate of lime, which, in most cases, will dissolve 

 every, thing but that sulphate, and which may thus be obtained and 

 weighed ; or, add oxalate of ammonia to a given quantity of the boiled 

 and filtered water, collect the precipitate, and give it a red-heat with 

 excess of sulphuric acid, by which it is converted into sulphate of lime, 

 equivalent to the original in the Avater. 



xcyi. Besides the substances now enumerated, and which may be 



