576 Mr. Warington on the 



the present day ; after this date the error of adding small por- 

 tions of spirit seems to have originated, and to have been 

 regularly copied, v/ith very little deviation, from edition to 

 edition, down to the year 1836, the general directions being to 

 distil a certain quantity of the water from a given weight of 

 material, and then to add five ounces of proof spirit to each 

 gallon, that it may he preserved, or rather 1 may say in many 

 cases, to spoil it. In the edition of 1836, the proportion of 

 spirit was increased to the formula that has been already given, 

 and this was also the form prescribed in some of the various 

 dispensatories about the middle of the eighteenth century. 



On examining into the quantity of acid generated in the 

 foregoing experiments, I found that half a pound of the car- 

 raway water required 4 grs. of dry carbonate of soda to effect 

 perfect neutralization, which is equivalent to 4*45 grs. of real 

 acetic acid. This acid was also isolated by distillation, and its 

 identity proved by various tests. 



We now pass on to the extemporaneous preparation of 

 flavoured waters from their respective essential oils. The gene- 

 ral formula given in the Pharmacopoeia of 1836, in which it 

 is introduced for the first time, is to triturate carefully toge- 

 ther one drachm of the essential oil with one drachm of car- 

 bonate of magnesia, and afterwards with four pints of distilled 

 water, and then strain. Now on examining the waters thus 

 prepared, they are all found, without exception, to contain a 

 notable quantity of magnesia, the proportions taken up seem- 

 ing to vary with the various essential oils employed, all other 

 circumstances remaining the same. Dr. Pereira, in his valu- 

 able ' Elements of Materia Medica,' vol. i. p. 258, speaks thus 

 of these waters : — " The magnesia (carbonate of magnesia) 

 effects the minute division of the oil. Moreover, when the 

 oils possess acid properties, as the old oils of pimento, cloves 

 and cinnamon, it probably serves to saturate them. Prepared 

 in this way the medicated waters usually contain a minute 

 portion of magnesia in solution : hence, by exposure to the air, 

 they attract carbonic acid, and let fall flocculi of carbonate of 

 magnesia. Moreover, the magnesia unfits them for the pre- 

 paration of solutions of some of the metallic salts, as bichloride 

 of mercury and nitrate of silver." 



The method of examination adopted in the following expe- 

 riments was to take a measured volume of the water, say 1000 

 grains, and evaporate it to dryness at a temperature not ex- 

 ceeding 212°, then to ascertain carefully the weight of the resi- 

 due, redissolve it in dilute acid, and test the resulting solution. 

 Magnesia in the form of carbonate was invariably found, to- 

 gether frequently, with resinous matter from the oil ; this was 



