In 1907, Charles A. Kraus identified the colour as being due to the presence of solvated electrons, which contribute to the high electrical conductivity of these solutions.
ɪn nˈaɪntiːnhˈʌndɹɪd sˈɛvən, tʃˈɑːɹlz ˈeɪ. kɹˈaʊs aɪdˈɛntᵻfˌaɪd ðə kˈʌlɚɹ æz bˌiːɪŋ dˈuː tə ðə pɹˈɛzəns ʌv sˈɑːlveɪɾᵻd ᵻlˈɛktɹɑːnz, wˌɪtʃ kəntɹˈɪbjuːt tə ðə hˈaɪ ᵻlˈɛktɹɪkəl kɑːndəktˈɪvᵻɾi ʌv ðiːz səlˈuːʃənz.