Louis Pasteur. In 1881-1885 Louis Pasteur first used animals as model for growing and studying viruses. He found that the rabies virus could be cultured in rabbit brains and discovered the rabies vaccine. However, Pasteur did not try to identify the infectious agent. The discovery of viruses. 1886-1903 â This period was the discovery period where the viruses were actually found. Ivanowski observed/looked for bacteria like substance and in 1898, Beijerink demonstrated filterable characteristic of the virus and found that the virus is an obligate parasite. This means that the virus is unable to live on its own.
The present gold holdings at the Fort Knox Gold Bullion Depository amount to approximately 147.3 million ounces worth more than 6 Trillion Dollars! Except for small samples removed to test its purity, no gold has been transferred to or from the Depository for many years.
The amount of gold in a necklace or ring is measured on the karat scale. Pure gold is 24 karats. Bars of gold kept in Fort Knox and elsewhere around the world are considered to be 99.95 percent pure, 24-karat gold.or example, 12 karat gold contains 50 percent gold and 50 percent alloys by weight. The word karat comes from the carob seed. In ancient Asian bazaars, the seeds were used to balance scales that measured the weight of gold. Follow Life's Little Mysteries on Twitter @llmysteries.