_The Ash._--100 c.c. of the wine are evaporated to dryness in a platinum dish, over the water-bath, and the residue is incinerated at a rather low temperature and weighed. By this process, the tartrates and malates contained in the wine are converted with carbonates. The ash of normal wine consists of potassium sulphate, carbonate, phosphate and chloride, sodium chloride, calcium carbonate, etc., but, in many samples, it will be found to be largely if not entirely composed of sulphates, which is due to the practice of sulphuring and plastering.[102] Generally speaking, the proportion of ash in genuine wine ranges from 0·15 to 0·30 per cent. _Chlorine._--100 c.c. of the sample are neutralised with sodium carbonate, evaporated to dryness, and the residue gently ignited. It is then extracted with boiling water, filtered, and the chlorine determined by means of silver nitrate, either volumetrically or gravimetrically. _Sulphuric Acid._--100 c.c. are acidulated with hydrochloric acid, the liquid heated to boiling, and the sulphuric acid precipitated by barium chloride. The precipitate is well washed, dried, and weighed. 100 parts represent 42·49 parts H_{2}SO_{4}. Pure wine contains from 0·109 to 0·328 gramme of monohydrated sulphuric acid per litre (corresponding to 0·194 to 0·583 gramme potassium sulphate). The presence of an excess of this maximum amount indicates that the wine has been plastered. _Phosphoric Acid._--100 c.c. of the wine are evaporated, the residue ignited, dissolved in a little water, acidulated with nitric acid, and then added to an excess of solution of ammonium molybdate. After standing over night the separated precipitate is dissolved in ammonia and the phosphoric acid determined by means of an ammoniacal solution of magnesium sulphate. 100 parts of the precipitate thus obtained correspond to 63·96 parts of phosphoric acid. The former belief that the best qualities of wine contain the largest proportion of phosphoric acid does not appear to be invariably correct. _Salicylic Acid._[103]--The determination of this acid is accomplished as follows:--100 c.c. of the sample are repeatedly agitated with chloroform, which is subsequently separated and evaporated to dryness. The residue is re-crystallised from chloroform and weighed; its identity can be established by dissolving it in water and adding solution of ferric chloride (see p. 149).