64 REPORT—1848. 
Alizaric'Acid.—In my former report I stated that alizarin, when treated 
with concentrated solutions of persalts of iron, is converted into a new acid, 
which I called alizaric acid. I stated at the same time that I thought it pro- 
bable that alizaric acid might also be formed by acting on alizarin with nitric 
acid. This supposition has since been confirmed. On treating pure cry- 
stallized alizarin with boiling nitric acid, it is decomposed with an evolution of 
nitrous acid, and the liquid on evaporation gives crystals of alizaric acid. It 
is however not necessary to prepare pure alizarin in order to obtain alizaric 
acid. I have found the following to be the easiest method :—Nitric acid of 
about sp. gr. 1'20 having been put into a retort, garancin is introduced into 
the acid, and the liquid is heated until the red fumes have ceased to be 
evolved, and the colour of the garancin has changed from dark brown to 
yellow. The reddish-yellow acid liquid which is obtained, is filtered or 
strained to separate it from the woody fibre, &c. of the garancin, and eva- 
porated to crystallization. A yellow crystalline mass is obtained, which is a 
mixture of oxalic acid and impure alizaric acid. After being washed with 
cold water to remove the excess of nitric acid, the mass is dissolved in 
boiling water, and chalk is added until all effervescence and acid reaction have 
ceased. The liquid is filtered, and the oxalate of lime remaining on the 
filter is washed with boiling water, until no more lime can be detected in the 
percolating liquid. he liquid is a solution of alizarate of lime. Muriatic 
acid is added to it, and it is evaporated to crystallization. A yellow mass is 
again obtained, which may be washed with cold water to remove the chloride 
of calcium, then redissolved in boiling water. It forms a yellow solution, 
which may be almost decolorized by animal charcoal. On again evapo- 
rating, the alizaric acid is obtained in large crystals. Should these crystals 
still retain a yellow tinge, which is generally the case, they must be re- 
dissolved in boiling water. By passing chlorine gas through the boiling 
solution, until every trace of colour has disappeared, perfectly colourless — 
crystals of the acid are obtained on cooling. Prepared in this way, it ap- 
pears in large flat rhombic plates: it has the properties which I described in 
my last report. 
The salts of alizaric acid are mostly soluble. Alizarate of potash is formed — 
by neutralizing a watery solution of alizaric acid with carbonate of potash : 
it is ébtained on evaporation as a deliquescent mass. Alizarate of lime is 
prepared by neutralizing alizaric acid with carbonate of lime, and evaporating 
to crystallization. It crystallizes in prisms, possessing great lustre. Alizarate 
of baryta, prepared in the same way by means of carbonate of baryta, cry- 
stallizes in silky needles. Alizarate of silver, prepared by double decompo- ~ 
sition, is soluble in boiling water, from which it crystallizes on the solution 
cooling. Alizarate of lead is an insoluble white powder, obtained by preci- 
pitation of the acid with sugar of lead. With ammonia alizaric acid does not 
seem to form a neutral salt. On supersaturating a solution of the acid with 
ammonia and evaporating, the solution acquires during evaporation an acid 
reaction, and at length a salt crystallizes out in flat plates, which is no doubt 
a superalizarate of ammonia. All the salts of alizaric acid, when strongly 
heated, are decomposed with an evolution of a fragrant smell similar to that — 
of benzin, and give, as a product of the decomposition, a thick brown oil, to 
which without doubt the smell is owing ; while the carbonates of the bases, 
or the bases themselves, remain behind mixed with much charcoal. 
The elementary analysis of alizaric acid gave the following results :— 
I. 0°5250 grm. obtained by means of perchloride of iron and burnt with — 
oxide of copper, gave 1°1015 carbonic acid and 0°1810 water. 
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