ADDITIONS AND NOTES TO VOL. I. 455 



at a temperature exceeding 200, in delicate, snowy crystals. 

 When rapidly heated it is partly decomposed; on being inflamed 

 it burns with a violet flame. By the action of nitrous acid, alanine 

 is decomposed into nitrogen, water, and lactic acid. 

 alanine are crystallisable, and more soluble than alanme itself m 

 water, as well as in alcohol and ether. 



From this beautiful discovery of Stacker's it seems almost 

 certain that lactic acid is formic acid coupled with aldehyde, 

 alanine consist of aldehyde and prussic acid, and if it is converted 

 by nitrous acid into lactic acid, we need only assume that (as oft< 

 occurs) the atoms of prussic acid are decomposed into formic acic 

 and ammonia, and that the latter is decomposed by nitrous acid 

 into nitrogen and water. Since, moreover, the products of decom- 

 position of the lactates (at all events of lactate of copper), support 

 the assumption that aldehyde pre-exists in lactic acid, this hypo- 

 thesis regarding the composition of lactic acid must be regard 

 as well established. 



(7) Note to p. 92, line 19.-[Scherer has recently published an 

 excellent memoir " On the recognition of small quantities of lactic 

 acid in animal matters," in the fourth volume of the Verhand- 

 lun^en der physicalisch-medicinischen Gesellschaft zu Wurzburg, 

 1854. After the coagulation of the albuminous matters either 

 by heat, or where this is not effectual, by alcohol, the filtered fluid 

 is evaporated to dryness, any membranes that may be formed 

 being removed. The residue is dissolved in water, and precipi- 

 tated with baryta-water, in order to remove the phosphoric acid, 

 sulphuric acid, and the earthy phosphates. The precipitate is 

 removed by nitration; the excess of baryta IS precipitated by 

 sulphuric acid, and the fluid again filtered. The filtrate is treated 

 with a little sulphuric acid, and is submitted to distillation, i: 

 order to separate the volatile acids ; viz., acetic, formic, butyric, and 

 hydrochloric acids. The residue left in the retort is very much 

 concentrated, treated with strong alcohol, and allowed to s and for 

 some days. The sulphates of potash and soda being mso uble in 

 alcohol, crystallise and adhere to the walls of the vessel. Tl 

 acid fluid is then decanted, and, after the addition of milk of lime 

 the alcohol is evaporated or distilled; we then filter while still 

 warm, and remove the excess of insoluble hydrate of hme and the 

 sulphate of lime that has been formed, and allow the filtered 

 neutral solution to stand for some days. If the fluid should stil 

 exhibit an alkaline reaction from the presence of dissolved 



