70 ALKALI 



of isinglass very copiously, liko infusion of galls and catechu. Its solution forms 

 with sulphate of iron a black precipitate. 



ALGERIAN ONYX, or ONTTX MARBLE. A stalagmitic carbonate of lime, 

 resembling the alabaster of the ancients. The chief quarries are at Ain-Tekbalet in 

 the province of Oran, in Algeria. The deposit there forms regular beds, nearly 

 horizontal, presenting a thickness of from 6 to 10 metres, and extending over an area 

 of more than 100 hectares. Originally the quarries wore worked by the Komans, and 

 subsequently by the Moors of Tlemcen. A few years ago they were re-discovered, 

 and are now actively worked ; the marble being highly prized as an ornamental stone. 

 A similar material has been found in the Caucasus, and is worked at Tiflis. 



AIiIMEMTT. (Alimcntum, from do, to feed). The food necessary for the human 

 body, and capable of maintaining it in a state of health. 



1. Nitrogenous substances are required to deposit, from the blood, the organised 

 tissue and solid muscle. 



2. And carbonaceous, non-nitrogenous bodies, to aid in the processes of respiration, 

 and in the supply of carbonaceous elements, as fat, &c., for the due support of animalheat. 



For information on these substances, consult Liebig's ' Animal Chemistry,' the 

 investigations of Dr. Lyon Playfair, and Dr. Kobert Dundas Thompson's ' Experi- 

 mental Researches on Food,' 1846. See FOOD. 



AXiXAXEltiTTARY SUBSTANCES. See NUTRITION. 



ALIZARINE. C 28 H 8 8 (C 14 H S O 4 ). One of the red colouring principles of 

 Madder. See MADDER. 



In 1869 Messrs. Graebe and Liebermann made the important discovery that 

 alizarine might be produced artificially from anthracene, one of the heavy products of 

 coal-tar distillation. Both scientifically and commercially, the discovery was one of 

 unusual interest : it furnished the first instance of the synthetical formation of an 

 organic colouring matter, and at the same time opened up a new branch of industry. 



According to Messrs. Graobe and Liobermann's original process, the anthracene was 

 first subjected to the action of certain oxidising agents, and thus converted into a 

 compound called anthraquinone or oxanthracene. This conversion may be effected by 

 heating one part of anthracene with two parts of bichromate of potash and sulphuric 

 acid, or by heating one part of anthracene with two parts of bichromate of potash 

 together with one part of glacial acetic acid. The anthraquinone thus obtained 

 is then converted into a bibromide by being heated with bromine. Finally, 

 this dibromanthraquine is heated to about 356 F. with caustic potash or soda, and 

 thus yields a blue product, which when cold is treated with water ; an excess of acid is 

 then added to the filtered solution, and the yellow precipitate thus thrown down is 

 washed and dried at a gentle heat. This precipitate is identical in chemical composi- 

 tion and in its properties with the alizarine of the madder-root. 



Valuable as these researches were in a scientific point of view, it remained for Mr. 

 Perkin to render the process economically available to the manufacturer by introducing 

 important modifications, whereby the use of an expensive agent like bromine was 

 dispensed with. Mr. Perkin showed that when anthraquinone is strongly heated with 

 sulphuric acid of specific gravity 1*84, it is converted into disulphoanthroquinonic 

 acid, and that this acid, when heated with hydrate of potash to a temperature of 

 356 F., ultimately yields sulphite and alizarate of potash, from which the alizarine 

 may be thrown down, as a bright yellow precipitate, by addition of hydrochloric acid. 



AXiKAXiX. A term derived from the Arabians, and introduced into Europe when 

 the Mahometan conquerors pushed their conquests westward. Al, el, or ul, as an 

 Arabic noun, denotes ' God Heaven Divine.' As an Arabic particle, it is prefixed 

 to words to give them a more emphatic signification, much the same as our particle 

 the ; as in Alcoran, the Koran, alchymist, tho chemist. 



Kali was tho old name for the plant producing potash (the glasswort, so called 

 from its use in the manufacture of glass), and alkali signified no more than tho kali 

 plant. Potash and soda were for some time confounded together, and wore hence 

 called alkalis. Ammonia, which much resembles them when dissolved in water, 

 was also called an alkali. Ammonia was subsequently distinguished as tho volatile 

 alkali, potash and soda being called fixed alkalis. Ammonia was also called tlio 

 animal alkali ; soda was tho mineral alkali, being derived from rock-salt, or from 

 the ocean ; and potash received tho name of vegetable alkali, from its source being 

 the ashes of plants growing upon tho land. Alkalis are characterized by being very 

 soluble in water, by neutralising the strongest acids, by turning to brown the vege- 

 table yellows, and to green tho vegetable reds and blues. 



Some chemists classify all salifiable bases under this name. 



In commercial language, the term has been hitherto applied to an impure soda, but 

 now it is understood to comprehend both soda and potash. The imports and exports 

 of tho alkalis are given on tho opposite page. See POTASH and SODA. 



