166 Dr. Schunck on the Action of 



by means of lime-water, and again strained, in order to separate 

 a small quantity of flocks thrown down by the lime. Sugar of 

 lead is now added to it, which produces a dirty, pinkish-white 

 precipitate. This is collected on a filter, washed with water, 

 and decomposed with sulphuretted hydrogen. The acid liquid 

 filtered from the sulphuret of lead is usually dark brown or 

 black, from sulphuret of lead in a state of suspension. During 

 evaporation, however, it deposits this sulphuret of lead, and after 

 being again filtered is clear, though still very brown. After 

 being evaporated almost to a syrup, milk of lime is added to it, 

 and the mixture is boiled. The lime removes a quantity of 

 phosphoric acid, which is probably derived from undecomposed 

 phosphates contained in the ferment, and also a great part of 

 the brown colouring matter. Through the filtered liquid, which 

 is much lighter in colour than before, I now pass a stream of 

 carbonic acid gas, until the excess of lime is completely neutral- 

 ized, after which it is evaporated almost to dryness. The car- 

 bonate of lime which is deposited during evaporation is separated 

 by filtration, and the liquid is evaporated with the addition of 

 an excess of muriatic acid, until it leaves a thick dark brown 

 syrup. In this syrup there is formed, after cooling and stand- 

 ing, a mass of crystals. These crystals must now be strongly 

 pressed between folds of blotting-paper, until the whole of the 

 syrupy mother-liquor containing chloride of calcium and other 

 impurities has been absorbed. The crystalline mass left on the 

 paper, which has a light brown colour, is now treated with boil- 

 ing alcohol, which leaves undissolved a quantity of sulphate of 

 lime. The alcohol, after filtration, is evaporated to dryness, the 

 residue is redissolved in boiling water, and the solution is deco- 

 lorized with animal charcoal. The solution now leaves on eva- 

 poration to dryness a colourless crystalline mass, consisting 

 partly of needles and plates, partly of crystalline crusts. Now 

 this crystalline mass is found to possess the properties of an acid 

 in a very marked manner. Its taste is at first strongly acid, but 

 this is immediately followed by a nauseous, somewhat metallic 

 after-taste. Its solutions redden litmus-paper strongly. When 

 heated on platinum-foil it melts and burns with a very pale 

 flame, leaving a slight carbonaceous residue. When heated in 

 a glass tube it melts, and crystallizes again on cooling. When 

 further heated it is volatilized, yielding fumes which strongly 

 afiect the nostrils and throat, produce a choking sensation, and 

 excite violent coughing. The fumes condense on the colder 

 parts of the tube, partly in the shape of needles, partly as a 

 white, crystalhne, radiated mass. Very little carbonaceous residue 

 is left, and even this is probably due to impurities, so that the 

 acid may be considered as completely volatile. The watery 



