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In Chapter 7, Thomson summarised his 1906 results on the number of electrons in an atom. He included one important correction: he replaced the beta-particle analysis with one based on the cathode ray experiments of [[August Becker]], giving a result in better agreement with other approaches to the problem.<ref name=Heilbron1968/>{{rp|273}} Experiments by other scientists in this field had shown that atoms contain far fewer electrons than Thomson previously thought. Thomson now believed the number of electrons in an atom was a small multiple of its atomic weight: "the number of corpuscles in an atom of any element is proportional to the atomic weight of the element — it is a multiple, and not a large one, of the atomic weight of the element."<ref>{{harvnb|Thomson|1907|p=27}}</ref> This meant that almost all of the atom's mass had to be carried by the positive sphere, whatever it was made of.
Thomson in this book estimated that a hydrogen atom is 1,700 times heavier than an electron ([[Proton-to-electron mass ratio|the current measurement is 1,837]]).<ref>{{harvnb|Thomson|1907|p=162}}: "Since the mass of a corpuscle is only about one-seventeen-hundredth part of that of an atom of hydrogen, it follows that if there are only a few corpuscles in the hydrogen atom the mass of the atom must in the main be due to its other constituent — the positive electricity."</ref> Thomson noted that no scientist had yet found a positively charged particle smaller than a hydrogen ion.{{sfn|Thomson|1907|pp=23, 26}} He also wrote that the positive charge of an atom is a multiple of a basic unit of positive charge, equal to the negative charge of an electron.<ref>J. J. Thomson (1907). ''The Corpuscular Theory of Matter''. p. 26-27: "In an unelectrified atom there are as many units of positive electricity as there are of negative; an atom with a unit of positive charge is a neutral atom which has lost one corpuscle, while an atom with a unit of negative charge is a neutral atom to which an additional corpuscle has been attached."</ref> Thomson refused to jump to the conclusion the the basic unit of positive charge has a mass equal to that of the hydrogen ion, arguing that scientists first had to know how many electrons an atom contains.<ref>Thomson (1907), p. 27: "Before we can deduce any conclusions as to the mass of the unit of positive electricity we must know something about the number of corpuscles in the system."</ref>
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