272 



ATTAR OF ROSES 



The term ' atomic weight ' was formerly employed as synonymous with ' chemical 

 equivalent,' but the ideas involved in the two terms, as applied in modern chemistry, 

 are essentially distinct. 



Every chemical manufacturer should be thoroughly acquainted with the combining 

 ratios, which are, for the same two substances, not only definite, but often multiple ; 

 two great truths, upon which are founded, not merely the rationale of his operations, 

 but also the moans of modifying them to useful purposes. The discussion of the 

 doctrine of atomic weights belongs to pure chemistry; but several of its happiest 

 applications are to bo found in the processes of art, as pursued upon the largest 

 scale. 



The following propositions may be regarded as the laws regulating atomic com- 

 bination : 



1. The combining proportions of elementary bodies -represent tic smallest .proportions 

 in which they enter into combination with each other 



2. The combining proportion of a compound body -is the sum of the combining pro- 

 portions of its elements. 



3. Combination takes place, whether between elements or compounds, either in the 

 proportions of their combining weights, or in multiples of these proportions, and never 

 in sub-multiples. 



4. The law of definite proportion teaches that individual compounds always contain 

 exactly the same proportions of their elements. See EQUIVALENTS, CHEMICAL. See also 

 Watts's ' Dictionary of Chemistry.' 



ATRAMElffTTTOX. An old name for iron-vitriol, or sulphate of iron. A 

 product of the partial oxidation of iron pyrites, which is sometimes- xiscd in making 

 ink. 



ATROPXHTE, or DATITRINE. C 34 H 23 N0 6 (C^H^JTO 1 ). An .exceedingly 

 poisonous alkaloid, found in deadly nightshade (Atropa Belladonna) and in stramo- 

 nium (Datura Stramonium), and probably in some other plantsi One-sixth of a grain 

 of atropine produces unconsciousness and delirium. To the freshly- prepared extract 

 of belladonna add a strong solution of caustic potash, and well mix in a -mortar. 

 Digest the resulting mass at a temperature of- 80 with benzole ; separate the latter, 

 and distil off the hydrocarbon in a retort on the water-bath. The residue in the 

 retort is to be treated with water acidulated with sulphuric acid ; the acid solution is 

 to bo precipitated by carbonate of soda, and the resulting atropino may then bo ob- 

 tained pure by crystallisation from alcohol. Atropino is used- in medicine, ith of a 

 grain being a full dose, and it is applied externally for producing dilatation of the 

 pupil of the eye. The smallest portion of a very dilute solution rubbed on the eyelid 

 suffices to produce the result. 



ATTALEA. A. funifera yields the coquil-la nut much used in -turnery. It was 

 formerly supposed that this species of Attalea also yielded the Piassaba fibre used 

 in Brazil for ropemaking, and in this country for the manufacture of bast-brooms, but 

 it is now known that the Piassaba fibre is the produce of another palm the Liopd- 

 dina Piassaba. See COQUILLA. 



ATTAR OF ROSES, more commonly, OTTO OF SOSES. An essential oil, 

 obtained in India, Turkey, and Persia, fro:n some of the finest varieties of roses. It 

 is procured by distilling rose-leaves with water, at as low a temperature as possible. 

 It is said that this perfume is prepared also by exposing the rose-leaves in water to 

 the sun; but, from the fact that under the circumstances fermentation would bo 

 speedily established, it is not probable that this is -a method often resorted to. ]>y 

 dry distillation from salt-water baths, no doubt the finest attar is obtained. This 

 essential oil is only used as a perfume. Attar of roses is adulterated with spermaceti 

 and with castor-oil dissolved in strong alcohol. 



This adulteration may bo detected by putting a small drop of the otto of roses on a 

 piece of clean writing-paper ; by agitation in the air, the 'Volatile oil soon evaporates, 

 leaving no stain if pure ; if any fixed oil is present, a greasy spot is -left on the paper. 



