h'olids, iiicliidijig pozo~lers.-Thc spcciinciis for spnrking nrc 11~1~1 in clips in an tidjustnblc liolclcr. This holdcr sufices for nict:iIs, alloys or conducting mincrnls.
If the spccimcns consist of non-conducting polvtlcrs (such ns tliosc of slags, precious stones, stouy iiincriils, glasses, precipitates or rcsidues from solutions), tlmc should be added n sinall cup of platinum about 20 inin. diainctcr nnd 5 mu. deep, held in tlic loivcr cianip by a wire of tiic snnic inctal, tlic clip being lieatcd in thc flnnic of : L Meker burner. it. stout platiiiiun wire lcnds thc spnrli from tlic uppcr clninp to tllc platinum cup, in which tlic powder or powdcrcd iiiincrnl is miscd and fuscd with about four tiincs its +eight of sodiuni or lithium carbonntc-these stilts bcing choscii becnusc of tlic simplicity of their spcctru.
h*qids.-Tf the samples arc in tlic form of solutions, tlic spiirkiiig titbcs of Hnrtlcy or of Pollok mny be The sct of photographs develops tip like t h t sho\w in Fig. , in which tlic tup spectriiin is of tin supposed to be pme, thc middlc is a coinniercial tin under examinntion, nnd the bottom is of lead, tlic mctaI \-hose prcsence or nbscnce is in question. It will be seen by the prescnce of thc scnsitire lines of wavcleiigt,hs 2614, 2663, 2803 nnd 2833, not only that the coininercial tin coutains sonic lend, but also, nS shown by line 2833, that R tmcc of lend is prcsciik in thc supposcdly piire mctnl. It is not, of coiirsc, necessary to adopt this prccisc arrangement of spectra, but it is one that is wry freqnently convcnient.
If esninin:itions for tlic prcsencc of otlicr inctnls require to hc n~acle on tlic sniiic saniplc'or if other saniples are to be tested, thr. snme plate can bc used by racking tlic dark slide to n frcsli position, and as ninny ns sis strips (tlint is, ciglitcen spectra iii all), will easily go on a single plntc.
In this way, and in otlier wiys ~vliich I will not stop to dcscribe, the entirc inctaIlic constitucnts in nii day, iniiicral, ash, or whatnot, can bc readily niid rliiickly idcntified.
adoptcd (SCC '< \:iivelengtll Tables lor Spectrulll Analysis," by F. T N ~~L I U ,