Faoi 1829, i stair an tábla pheiriadaigh, luath iarracht ab ea triaid Döbereiner na dúile a shórtáil in ord loighciúil éigin de réir a n-airíonna fisiciúla. Sa bhliain 1817, thuairiscigh litir faoi bharúlacha Johann Wolfgang Döbereiner ar na miotail chré-alcaileacha; is é sin, go raibh airíonna ag an strointiam a bhí idirmheánach dóibh siúd a bhí ag cailciam agus bairiam.[1] Faoi 1829, bhí grúpaí eile de thrí dhúil (mar sin "triaid") aimsithe ag Döbereiner a raibh baint chéanna ag a n-airíonna fisiciúla leo.[2] Thug sé faoi deara freisin gur lean roinnt airíonna inchainníochtaithe de dhúile (m.sh. meáchan adamhach agus dlús) treocht trína ndéanfaí luach na dúile lárnaí sa triad a thuar go díreach nó beagnach trí mheán uimhríochtúil luachanna don mhaoin sin den dá dhúil eile a thógáil.

Johann Wolfgang Döbereiner, a rinne iarracht na dúile a shórtáil in ord a bhí comhdhéanta de thriaid.
Mais adamhach tuartha vs mais adamhach iarbhír d'adamh lárnach i ngach triad
Ainm an triaid[2] Dúile agus maiseanna adamhacha[2][3]
Dúil 1
Mais
Dúil 2
Meán of 1 and 3
Mais iarbhír
Dúil 3
Mais
Dúile a chruthaíonn miotail alcaile Litiam
6.94
Sóidiam
23.02
22.99
Potaisiam
39.10
Dúile a chruthaíonn miotal chré-alcaileacha Cailciam
40.1
Strointiam
88.7
87.6
Bairiam
137.3
Dúile a chruthaíonn salann Clóirín
35.470
Bróimín
80.470
78.383
Iaidín
126.470
Dúile a chruthaíonn aigéad Sulfar
32.239
Seiléiniam
80.741
79.263
Teallúiriam
129.243
Triad iarainn Iarann
55.8
Cóbalt
57.25
58.9
Nicil
58.7
  1. "Auszug eines Briefes vom Hofrath Wurzer, Prof. der Chemie zu Marburg" (as German) (1817). Annalen der Physik 56 (7): 331–334. doi:10.1002/andp.18170560709. Bibcode1817AnP....56..331..  From pp. 332–333: "In der Gegend von Jena (bei Dornburg) … Schwerspaths seyn möchte." (In the area of Jena (near Dornburg) it is known that celestine has been discovered in large quantities. This gave Mr. Döbereiner cause to inquire rigorously into the stoichiometric value of strontium oxide by a great series of experiments. It turned out that it [i.e., the molar weight of strontium oxide] – if that of hydrogen is expressed by 1 or that of oxygen is expressed by the number 7.5 – is equal to 50. This number is, however, precisely the arithmetic mean of that which denotes the stoichiometric value of calcium oxide (= 27.55) and of that which denotes the stoichiometric value of barium oxide (= 72.5) ; namely (27.5 + 72.5) / 2 = 50. For a moment, Mr. Döbereiner found himself thereby caused to doubt the independent existence of strontium; however, this withstood both his analytical and synthetic experiments. Even more noteworthy is the circumstance that the specific weight of strontium sulfide is likewise the arithmetic mean of that of pure (water-free) calcium sulfide and that [i.e., the sulfide] of barium, namely (2.9 + 4.40) / 2 = 3.65 ; which must cause [one] to believe even more that celestine might be a mixture of equal stoichiometric amounts of anhydrite [i.e., anhydrous calcium sulfate] and barite.)
  2. 2.0 2.1 2.2 Döbereiner (1829). "Versuch zu einer Gruppirung der elementaren Stoffe nach ihrer Analogie" (as German). Annalen der Physik und Chemie 15 (2): 301–307. doi:10.1002/andp.18290910217. Bibcode1829AnP....91..301D.  For an English translation of this article, see: Johann Wolfgang Döbereiner: "An Attempt to Group Elementary Substances according to Their Analogies" (Lemoyne College (Syracuse, New York, USA))
  3. Tá ort na shonrú' 'teideal = agus' 'url = nuair a úsáideann {{ lua idirlín}}."". Cartlannaíodh an bunleathanach ar 2016-03-23.