D. B. Spoelstra — properly Dr. D. B. Spoelstra — was a Dutch chemist of the Afdeeling Handelsmuseum of the Koninklijke Vereeniging Koloniaal Instituut in Amsterdam who, in 1930, performed the fractional distillation of the Atjeh-turpentine samples that established the chemical basis of the improved quality of the factory-scale product. He is named in the Atjeh-terpentijn pamphlet of 1930 as the author of the chemical investigation that identified the fourfold reduction in carene content — from 15% in the 1924 trial samples to about 4% in the 1930 factory product — as the chemical basis of the improved odour of the new Baleq turpentine.
The chemical investigation
The Atjeh-terpentijn pamphlet records that, in order to determine whether the changes in the chemical properties of the new product — relative to the trial samples of 1924 — were accompanied by a change in chemical composition, Dr. Spoelstra subjected a larger quantity of the new turpentine to a fractional distillation. The distillation was performed on 2500 g of oil (sample H.M. no. 1607) under a pressure of 30 mm, and the resulting fractions were examined individually. The first four fractions — totalling 2046 g — consisted of d-α-pinene in, by all observable constants, pure form. The fifth fraction — 270 g — was also principally pinene, so that the actual pinene content was judged to lie between 85% and 90%. The sixth fraction — 227 g — was subjected to further fractional distillation, and from it Spoelstra isolated 93 g (approximately 4%) of Δ3-carene in nearly pure form: boiling point 169–173 °C at 760 mm, density d⁴ = 0.8636, refractive index n² = 1.4723, optical rotation α +12.2°. The identification was confirmed by the preparation of the nitrosate, which after recrystallisation melted at 146 °C.
The carene content of approximately 4% in the 1930 factory product — against approximately 15% in the 1924 trial samples — was the chemical basis of the improved odour of the new Baleq turpentine. The same investigation isolated a small quantity of sesquiterpenes (3.6 g, or 0.15%), which after distillation over sodium showed the constants characteristic of bisabolene.
Other publications
The list of Berichten van de Afdeeling Handelsmuseum preserved at the back of the Atjeh-terpentijn pamphlet records that Spoelstra was the author, with A. Reclaire, of Bericht No. 25 (Kajoeputih-oil (Cajeputolie), 1926), No. 31 (Over de bepaling van het z.g. total-geraniol-gehalte in Java-citronellolie en over het analytisch onderzoek van die olie in het algemeen, 1927), No. 36 (Verdere mededeelingen over de bepaling van het z.g. total-geraniol-gehalte in Java-citronellolie en over het analytisch onderzoek van die olie in het algemeen, 1928) and No. 54 (Over de cineolbepaling in kajoeputiholie, 1930); and the author of Bericht No. 41 (Onderzoekingen over Bambang-olie en Kajoepoetih-olie, 1929). The range of his publications — from Atjeh-turpentine to Java-citronella oil, from cajeput oil to barnes-kamfer — indicates that he was the Koloniaal Instituut’s principal chemical researcher on essential oils.
Significance
Spoelstra’s significance in the historiography of colonial Aceh is as the chemist whose fractional distillation of the Atjeh-turpentine samples established the chemical basis of the improved quality of the factory-scale product. His identification of the fourfold reduction in carene content — from 15% to 4% — as the chemical basis of the improved odour is the principal scientific result of the Atjeh-terpentijn evaluation of 1930, and his work on the chemical composition of Atjeh-turpentine is the principal published scientific investigation of the subject.
See Also
- Atjeh-terpentijn (Spoor, 1930)
- Atjeh-terpentijn
- Afdeeling Handelsmuseum
- Koninklijke Vereeniging Koloniaal Instituut
- W. Spoon
- L. P. de Bussy
- M. A. van Royen
- Baleq
- 1930
Source
Atjeh-terpentijn: tegenwoordige kwaliteit en nieuwe beoordeelingen, by Ir. W. Spoon, Berichten van de Afdeeling Handelsmuseum van de Koninklijke Vereeniging Koloniaal Instituut No. 57, Amsterdam: J. H. de Bussy, 1930, pp. 12–13 (Scheikundige samenstelling en eigenschappen).