CHEMISTRY. 



[r.NIlEALTHY MANUFACTURE*. 



by humane endeavours. At all eventm, we may rent quito 

 assured that uo manufacture can be legitimately carried on 

 winch mutt ncceasarily cause the death of its labourers ; 

 and we may equally be oerUin, that an, in manufacturing, 

 we mcn-ly avail ourselves of the lawi of nature applied 

 for B|ctal purposes, there are inch methods of con- 

 ducting our prooesM* as shall render them quite con- 

 sistent with sanitary requirements, if our prejudices and 

 ignorance do not stand in the way. 



Much foolish prejudice, however, exists in the mind 

 of the public against all places in which chemical sub- 

 stances are produced ; and hence sulphuric acid and 

 soda manufacturers have been the subjects of considerable 

 persecution. In many cams, positive benefit may arise 

 from the purification and diunfectation of tbe sewers, 

 by the waste running from such factories. We have 

 in. t with several instances of the kind in London, and 

 other large cities, presenting cases in which whole streets 

 have been protected fiom disease by this cause. The 

 erection of tall chimneys for carrying off the fumes and 

 vapours, and an abundant supply of water, will generally 

 remove all sources of danger. It is, however, extremely 

 desirable that competent inspectors should be appointed, 

 whose duties should not be confined to the prevention 

 of nuisance tnittitie the factory, but who should also 

 have a judicious control over the internal arrange- 

 ments, and thus be enabled to keep a watchful eye on 

 the health of the work-folks iiuide the gates. It will 

 frequently be found that the ill-health of labourers in 

 chemical works, does not so much arise from the inha- 

 lation of fumes, tire,, as from their constant exposure to 

 changes of temperature, and from the fact that most of 

 the processes are carried on in open sheds, affording little 

 or no protection from draughts of air, and wet weather. 

 By these the strongest man must soon be reduced to a 

 state of disease, through checked perspiration, <tc. 



Two singular instances, in which the production of 

 disease seems at first sight unavoidable, are those of glass- 

 silvering, and lucifer match-making. In both of these, 

 the vapour of the substances used seems to be absorbed 

 by the worker, until his entire frame is permeated. In 

 silvering glasses, large quantities of quicksilver are used. 

 The progress of disease is noted by the salivation pro- 

 duced ; and at last the individual becomes almost a com- 

 plete carious mass. In making lucifer-matches, the 

 phosphorus is similarly absorbed by the system, affect- 

 ing the bones of the face and palate until these are com- 

 pletely eat away. But in this extreme case a remedy 

 has been discovered ; for if amorphous phosphorus be 

 employed,* all danger vanishes, and the work people 



Set antr, p. 370. 



suffer no inconvenience of any kind. On the continent, 

 the use of the ordinary phosphorus is forbidden, for the 

 foregoing reason, and thus a most painful and incurable 

 disease is prevented. 



Our space will not permit us to enlarge further on 

 this interesting subject, or we might point out several 

 instances in which the employment of poisonous sub- 

 stances is not only dangerous, but positively wicked. 

 The manufacture of green artificial leaves, <tc., is 

 cam is 1 on by the use of the arseniate of copper. Scores 

 of young females are hourly exposed to the pernicious 

 dust of the compound in close rooms, for no other pur- 

 pose than to administer to the vanity of others, t No 

 one can hesitate to pronounce against such occupations, 

 whether in respect to the evil resulting to the workers, 

 or to the danger which most certainly arises from wear- 

 ing the product of their labours. In many a ball-room, 

 the ladies carry, in their ornaments and dross, as much 

 arsenic as would suffice to poison all present ; and, 

 generally, the arsenical dust is wafted from their dresses 

 and head-dresses, in quantities of which they have but 

 little idea. This is one out of many similar employments 

 in which females are engaged ; and may thus serve as a 

 type of manufactures, which less devotion to fashion 

 would at once cause to bo abolished ; and in being carried 

 on, serve no useful end. 



The following Tables of WEIGHTS AND MF.ASCTRF.S will 

 be found useful by the student A more extended series 

 will be given in connection with Applied Mechanics. 



ENGLISH WEIGHTS. 



Gralni. Ounce*. 



Troy weight . . . j 

 Avoirdupois weight j 



480 

 6700 



437| 

 70UO 



1 

 12 



1 

 16 



Pound. 

 = 1 



= 1 



FRENCH WEIGHTS. 



The standard is the gramme = 15-434 troy grains; 

 and the decimal system is adopted. Thus the 



Milligramme = -015434 



Centigramme = -154340 



Decigramme. = 1-643400 



Gramme . = 15-434000 



Decagramme = 154-340000 



Hectogramme = 1543400000 



Kilogramme. = 15434-000000 = 2J 



pounds avoirdupois weight, English, 

 t See ante, p. 981. 



ADDENDA. 



THE NEW METAL, THALLIUM. 



In the chapter treating on Metals,* we have mentioned 

 the discovery of two, by means of the spectrum analysis ; 

 and an extended use of the same agency has resulted 

 in the addition of a third to that class of elementary 

 bodies. In the Great Exhibition of 1802, a few grains 

 of this metal were exhibited, which had been obtained 

 from the residue of a process for making sulphuric acid. 

 IU discovery arose from a rich green spectral band being 

 produced, when a portion of the material above named 

 was submitted to the spectrum examination ; and the 

 name Thallium was applied to it, on account of the 

 colour of the flame. Since that time Mr. Crookes has 

 duvotud his attention to the production of the metal 



Bt ar<r,p. 312. 



on a larger scale ; and has so far succeeded as to have 

 prepared several ounces. In its physical character it 

 resembles lead, being very soft, marking paper like that 

 metal, and having a specific gravity of 11-4. Its che- 

 mical equivalent is 203. It forms two or three oxides ; 

 and unites with acids, affording salts, which crystallise in 

 beautiful forms. The chief sources have hitherto been 

 substances united with sulphur such as native sulphur- 

 ores of copper, &o. The small quantities, comparatively 

 speaking, yet procured, have not enabled .Mr. Crookes 

 to give a probable estimate of its commercial value and 

 application ; but, as it seems pretty widely disseminated 

 in mineral bodies, it may possibly become of some 

 importance in tue arts and manufactures. 



