Gas-vapour LampsSCIENTIFIC research workers have opened a new field for China - the use of gases in place of metal filaments as a source of electric light. They have trial-produced more than 30 types...
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Gas-vapour LampsSCIENTIFIC research workers have opened a new field for China - the use of gases in place of metal filaments as a source of electric light. They have trial-produced more than 30 types...