270 



KNOWLEDGE. 



[NOVEMBEB 1, 1897. 



" morning tonic," or " pick-me-up," the point at issue 

 being whether the preparation was a medicine or a beverage. 

 A chemist at Sunderland, not being licensed for the sale 

 of methylated spirit, was asked for a gill by an Inland 

 Kevenue officer, and said he must put something in it 

 before he could sell it. He added some resin, but according 

 to the evidence for the prosecution did not add in the 

 proportion of three ounces to the gallon — the regulation 

 amount. 



The formalities to be observed when a purchase is made 

 for the purpose of analysis, either by a private individual 

 or an officer, must be rigidly observed. The person pur- 

 chasing any article with the intention of submitting the 

 same to analysis shall, after the purchase shall have been 

 completed, forthwith notify to the seller, or his agent 

 selling the article, his intention to have the same analyzed 

 by the public analyst, and shall offer to divide the 

 article into three parts, to be then and there separated, 

 and each part to be marked and sealed, or fastened up in 

 such a manner as its nature will permit ; and shall, if 

 required to do so, proceed accordingly, and shall deliver 

 one of the parts to the seller or his agent. He shall 

 afterwards retain one of the said parts for future com- 

 parison, and submit the third part, if he deem it right to 

 have the article analyzed, to the analyst. 



On entering the main laboratory a scene of extreme 

 activity presents itself, and one is almost bewildered by 

 the variety of operations in which the many chemists are 

 continuously engaged. The profuse distribution of bottles 

 of all kinds of alcoholic drinks, tinctures, etc., on the top 

 shelves of the benches, and the manner in which the malt 

 liquors are being transferred from vessel to vessel, gives 

 one the impression of a busy bar in some public-house. 

 A little friendly explanation, however, from the courteous 

 and extremely intelligent workers, eliminates much of the 

 mystery with which the processes are at first sight invested. 

 The operation of " tossing " beer, for example, is per- 

 formed for the purpose of extracting the free carbonic 

 acid locked in the liquid during fermentation. As the 

 beer is poured from a great height an abundance of froth 

 rises to the surface, and, as the bubbles break, carbonic 

 acid escapes. A measured quantity of the beer is then 

 weighed for the purpose of determining its specific gravity, 

 and it is then put in a still, by which means the alcohol, 

 under the influence of heat, distils over into a receiver, 

 the boiling point being much lower than that of water. 

 In this way a distillate is obtained richer in alcohol than 

 the original beer, and the distillate, when weighed in the 

 balance, indicates a difl'erent specific gravity, which enables 

 the chemist to compute the percentage of alcohol in the 

 sample of beer under examination, account also being 

 taken of the solid residue left in the still. 



In another laboratory an assistant may be seen in- 

 vestigating, say, samples of butter. How can he detect 

 foreign matter ? One method is by means of a specially 

 constructed microscope. The pure article, when melted 

 and a ray of light passed through it, has a definite 

 refractive index for a given temperature, and when foreign 

 matter is present the refractive index varies according to 

 the nature of the substance added. Hence, a sample of 

 butter is put in the instrument, and melted by water from 

 a conical vessel introduced into a jacket in the microscope 

 by means of tubing. The temperature is then registered 

 by a thermometer, and the refraction is read off on a 

 graduated scale in the field of view. Again, a sample of 

 steel may be under examination for sulphur, and if more 

 than a regulation amount is found the steel is condemned 

 as unfit for a particular purpose. The steel, as filings, is 

 dissolved in acid in a flask, by which means the sulphur in 



it is set free, and this free sulphur is converted into 

 sulphuretted hydrogen by means of a current of hydrogen 

 urged through from a Kipp's apparatus, the hydrogen being 

 washed from impurities on its way to the flask by a proper 

 solvent in a Wolf's bottle. The sulphuretted hydrogen 

 thus formed passes onwards to another flask containing 

 lead nitrate, by which means lead sulphide is formed. By 

 means of an oxidizing agent this lead sulphide is converted 

 into lead sulphate, a definite compound in which the pro- 

 portion of sulphur is known. And so the sulphur which 

 before existed in the steel in an unknown proportion, is 

 now united with lead in such a ratio as admits of computing 

 its proportion in the original sample of steel, a definite 

 weight of the steel having been taken for analysis. 



Still, used in distilling Alcoliolic Liquids. 



The work of the institution is divided into four distinct 

 departments : (1) the main laboratory, wholly reserved for 

 the analysis of alcoholic products — beer, wines, tinctures, 

 rum, brandy, etc. ; (2) the tobacco rooms, fitted with 

 appliances for the examination of manufactured and the 

 so-called " offal " tobacco, for the determination of fraudu- 

 lent or improper admixtures ; (3) the Board of Agriculture 

 Department, where all • cases of disputed analyses of 

 fertilizers, feeding stuffs, etc., are referred by magistrates, 

 and on which the decision of the Principal Chemist is final ; 

 (4) the Crown contracts laboratories, in which all manner 

 of substances may from time to time be examined — from 



